Following the parentheses are two braces. The first brace denotes the beginning of a logical programming block and the last brace denotes the end of a logical programming block. The following program code demonstrates a complete, simple C program. From this code, you will learn how single program statements come together to form a complete C program.
Review the sample program code in Figure 1. Comments help to identify program purpose and explain complex routines. They can be valuable to you as the programmer and to other programmers looking at your code. These character sets are not required to be on the same line and can be used to create both single-line and multi-line comments. To demonstrate, the following block of code shows the usefulness of multi-line commenting. For example, the following code segment leaves out a comment character set and will not compile.
The next line of code demonstrates this. Though unlikely, be aware that not all C compilers support the single line character set. For example, the following code creates a multi-line comment block. These keywords have predefined uses and cannot be used for any other purpose in a C program.
These keywords are used by the compiler, in this case gcc, as an aid to building the program. Note that these keywords must always be written in lowercase see Table 1. TABLE 1. If it does, they will be listed in the documentation that came with your compiler. As you progress through this book, I will show you how to use many of the aforementioned C language keywords.
Many of these program statements must end with a statement terminator. Statement terminators are simply semicolons ;. The next line of code, which includes the printf function, demonstrates a program statement with a statement terminator. Only C statements that perform work during program execution require the semicolons. A function commonly used for displaying output to the computer screen is the printf function.
For the most part, characters or text that you want to appear on-screen are put inside quotation marks, with the exception of escape characters or escape sequences.
When the printf statement shown above is executed, the program looks forward to the next character that follows the backslash. In this case, the next character is the character n.
Escape Sequences Escape sequences are specially sequenced characters used to format output. Take a look at the following program statement. How many new lines are added to standard output with this one printf function? Before any text is shown, the program outputs a new line. After the text is written to standard output, in this case the computer screen, another new line is written. Table 1.
This escape sequence is useful for formatting output in many ways. For example, a common formatting desire is to create columns in your output, as the following program statements demonstrate. The following program code demonstrates how it works; the output is shown in Figure 1. This may seem unnecessary at first, but remember that whenever the program reads a backslash in a printf function, it expects to see a valid escape character right after it.
The output is shown in Figure 1. In the preceding example, I told the preprocessor to include the stdio. The name stdio. It contains links to various standard C library functions, such as printf. Excluding this preprocessor directive will not have an adverse affect when compiling or running your program. However, including the header file allows the compiler to better help you determine error locations.
You should always add a directive to include any library header files that you use in your C programs. In the chapters to come, you will learn other common library functions, how to use other preprocessor directives such as macros, and how to build your own library files. A C program goes through a lot of steps prior to becoming a running or executing program. The gcc compiler performs a number of tasks for you. Use the.
This extension is the standard naming convention for programs created in C. To create a new C program, invoke a text editor such as nano or VIM as shown next. From an end-user perspective, it is much more intuitive and easier to use than VIM, but it does not have the amount of functionality as VIM. Though not selected in a default installation of Cygwin, nano and other text editors can be selected during installation via the Select Packages window. Both of the preceding command statements open a text editor and create a new file called hello.
Every time you compile a C program with gcc, it overwrites the previous data contained in the a. You can correct this by supplying gcc with an option to specify a unique name for your executable file. The syntax for specifying a unique executable name is as follows. By preceding the name of your compiled program with the. Note that in both cases it is not necessary to follow the compiled program name with the file extension. A fair amount of your programming time will be spent finding and removing these bugs.
This section provides some tips to help you get started. Remember, though, that debugging is as much art as it is computer science and, of course, the more you practice programming the easier debugging will become! For example, the following program and its output shown in Figure 1. Can you see where the format issue or issues are? The next block of code and its output in Figure 1. Format issues are common in beginning programming and are typically quickly resolved by practicing the printf function and the various escape sequences.
The first step in debugging a logic error is to find the first line where the program bug exists. One way of doing this is through print statements, using the printf function, scattered through your code. The stdout parameter passed to the fflush function is the standard output, generally the computer screen. After you have narrowed down the line or function where your logic error occurs, the next step is to find out the value of your variables at that time.
You can also use the printf function to print variable values, which will aid you greatly in determining the source of abnormal program behavior. Displaying variable values using the printf function will be discussed in Chapter 2 in detail.
Remember, after you fix any bug, you must recompile your program, run it, and debug it again if necessary. Debugging compile errors can be a daunting task, especially when you see 50 or more errors on the computer screen. One important thing to remember is that a single error at the top of your program can cause cascading errors during compile time.
So it goes without saying that the best place to start debugging compile errors is with the first error on the list! Figure 1. When debugging compile errors, remember to simply start with the first error, shown next, which tells me that I have an error right before the printf function. You will find that after solving the first error, many of the remaining errors no longer exist. This type of parse error can be generated for a couple of reasons.
In addition to missing program block identifiers, parse errors can occur because of missing statement terminators semicolons. Can you see where the bug exists? Parse errors occur because the C compiler is unable to determine the end of a program statement such as print statement. In the example shown in Figure 1. Common Error 3: Invalid Preprocessor Directives If you type an invalid preprocessor directive, such as misspelling a library name, you will receive an error message similar to Figure 1.
The following program block with a misspelled library name in the preprocessor directive caused the error generated in Figure 1. Can you see the error? The library name for standard input output should be spelled stdio. Common Error 4: Invalid Escape Sequences When using escape sequences it is common to use invalid characters or invalid character sequences. For example, Figure 1. Specifically, it notes that the error is on line 7 and that it is an unknown escape sequence. Can you identify the invalid escape sequence in the following program?
Common Error 5: Invalid Comment Blocks As mentioned earlier in the comment section of this chapter, invalid comment blocks can generate compile errors, as shown in Figure 1. Study the nano Quick Guide as described in Appendix C. Create a program that prints your name. Write a program that prints a diamond as demonstrated next. Create a calendar program using the current month similar to the one shown in Figure 1.
In addition to beginning data types, you will also learn how to display variable contents using the printf function and to manipulate data stored in variables using basic arithmetic. In Chapters 10 and 11, you will learn how to use nonvolatile memory for storing data. Volatile memory loses its data when power is removed from the computer. RAM is comprised of fixed-size cells with each cell number referenced through an address. Programmers commonly reference memory cells through the use of variables.
There are many types of variables, depending on the programming language, but all variables share similar characteristics, as described in Table 2. The hexadecimal numbering system is sometimes used in advanced C programming to reference concise memory addresses, such as during system-level programming.
Integer data types hold a maximum of four bytes of information and are declared with the int short for integer keyword, as shown in the following line of code.
Remember from Chapter 1 that executable program statements such as a print statement or in this case a variable declaration require a statement terminator ;. Floating-Point Numbers Floating-point numbers are all numbers, including signed and unsigned decimal and fractional numbers.
Signed numbers include positive and negative numbers whereas unsigned numbers can only include positive values. Examples of floating-point numbers are shown in the following list. Characters Character data types are representations of integer values known as character codes. For example, the character code 90 represents the letter Z. Note that the letter Z is not the same as the character code , which represents the letter z lowercase letter z.
In all, there are a total of common character codes 0 through , which make up the most commonly used characters of a keyboard.
In C, character variables are created using the char short for character keyword as demonstrated next. It is never safe to assume that the newly assigned variable location is empty. To prevent unwanted data from appearing in your newly created variables, initialize the new variables, as shown below. After creating the two variables, I initialize them to a particular value.
Notice that in the character variable data assignment I enclosed the NULL character in single quotes. Single quotes are required when assigning data to the character data type. Although NULL data types are a common computer science concept, they can be confusing.
Essentially, NULL characters are unknown data types stored in a memory location. When assigning data to variables such as variable initialization, the equal sign is not used in a comparative sense. In other words, you would not say that x equals 0. Rather, programmers say variable x is taking on the value of 0. Remember, when assigning data to variables, such as initializing, you refer to the equal sign as an assignment operator, not a comparison operator. The preceding code is a complete C program that demonstrates many of the topics discussed thus far its output is shown in Figure 2.
You can accomplish this seemingly difficult task using character sets known as conversion specifiers. Table 2. TABLE 2. Each variable displayed using a printf function must be outside the parentheses and separated with a comma ,. The following printf function demonstrates the precision problem. My Initials are M. Notice in the statement below that each variable displayed with the printf function is outside the double quotes and separated with a single comma.
They are most commonly used when you need to reuse a common data value without changing it. Constant data values can be of many data types but must be assigned when the constant is first created, as demonstrated next. Just as a bridge provides function, it can also provide beauty, eye candy for both the structural engineer as well as the traveler. You should stick with a style and convention that allow you or someone else to easily read your code. Once you pick or become comfortable with a programming style, the name of the game is consistency.
When learning how to program you should specifically consider at least two areas to develop a consistent programming convention and style. So what is white space? Philosophically speaking, white space is your programming canvas.
A few examples of how white space can be controlled are with braces and indentation. Indentation is a must as it guides your eyes in and out of program control. For example, looking at the following sample main function, your eyes quickly tell you the code inside the function logically belongs to it.
This argument can be settled pretty easily in favor of spaces. The rationale behind this favor is based on the fact that tabs can be set to take up various columns. Another programmer opening your code might not have the same number of columns set for her tabs and consequently the formatting will be off.
Another common question with beginning programmers is how far to indent. Personally, I prefer an indentation of two to four spaces. An indentation of longer than four spaces will eventually lead to lines that are too long. The goal here is to maintain a consistent indentation style that keeps the lines of code on the computer screen.
One more thing to consider regarding white space is your brace styles, which are closely tied to your indentation style. Variable Naming Conventions The following list contains a minimal number of guidelines you should follow when declaring and naming your variables. After identifying your naming standards, the most important process is to stay consistent with those practices throughout each of your programs. TR AP In addition to adhering to a variable naming convention, be cautious not to use reserved characters in your variable names.
Identifying Data Types with a Prefix When working with variables, I tend to choose one of three types of prefixes, as demonstrated next. When I see these variables in my program code, I know instantly what data types they are.
Another way of prefixing your integer data types is to use a single-character prefix, as shown in the second variable declarations. Also, these single-character prefixes work very well when used in conjunction with appropriate upper- and lowercase letters, as discussed in the next section. Now, take a look at the same variables with the same name, only this time without using uppercase characters. In addition to using uppercase letters for readability, some programmers like to use the underscore character to break up words, as shown in the following code.
Constant data types provide another challenge for creating a standard naming convention. Personally, I like the following naming conventions. Notice, though, that I still capitalize the first letter in the constant name for readability purposes.
In the second declaration, I simply capitalize every letter in the constant name. This naming style really stands out. Doing so creates self-documenting code. Instead, look at the following self-documenting variable names. In this section, you will learn how to receive input from users through the scanf function.
The scanf function is another built in function provided by the standard input output library ; it reads standard input from the keyboard and stores it in previously declared variables. It takes two arguments as demonstrated next. You can use the same conversion specifiers as discussed in Table 2.
Its output is shown in Figure 2. The first notable line of code prompts the user to enter a number. The next line of code uses the scanf function to receive input from the user. Essentially, the address operator contains a pointer to the location in memory where your variable is located. For now, just know that you must precede variable names with it when using the scanf function. After receiving both numbers operands from the user, I then use a print statement to display the following result.
In the Adder program from the previous section, I used a shortcut when dealing with common arithmetic: I performed my calculation in the printf function. Although this is not required, you can use additional variables and program statements to derive the same outcome.
For example, the following code is another variation of the Adder program that uses additional program statements to achieve the same result. For example, you would not say the following: iResult equals iOperand1 plus iOperand2. That is incorrectly stated.
Instead you would say: iResult gets the value of iOperand1 plus iOperand2. Operator precedence in C is shown in Table 2. Take another look at the same implementation in C —this time without using parentheses to dictate the correct order of operations. All of the C code needed to create the Profit Wiz program is demonstrated next. Identify data types with a prefix. Use upper- and lowercase letters appropriately.
Give variables meaningful names. Create a program that uses the same formula above to output the result; this time, however, prompt the user for the values a , b, x , and y. Use appropriate variable names and naming conventions. Create a program that prompts a user for her name. Conditions often called program control, decisions, or expressions allow you to make decisions about program direction. Learning how to use and build conditions in your program code will give you a more fluid and interactive program.
Along the way, I will introduce essential beginning computer science theories that will help you learn the fundamental concepts of algorithm analysis and Boolean algebra. Reviewing these topics will provide you with the necessary background for understanding conditional program control. In fact, many computer science professors say that computer science is really the analysis of algorithms.
An algorithm is a finite step-by-step process for solving a problem that begins with a problem statement. It is this problem statement that programmers use to formulate an algorithm for solving the problem. Keep in mind, the process of building algorithms and algorithm analysis occurs before any program code has been written.
To get a visual picture of algorithms, programmers and analysts commonly use one of two tools to demonstrate program flow the algorithm.
In the next few sections, I will show you how to build and use two algorithm tools: pseudo code and flowcharts.
Expressions and Conditional Operators Conditional operators are a key factor when building and evaluating expressions in pseudo code, flowcharts, or any programming language. Not all programming languages, however, use the same conditional operators, so it is important to note what operators C uses.
Table 3. Programmers use pseudo code as a shorthand notation for demonstrating what an algorithm looks like, but not necessarily what the program code will look like. Once the pseudo code has been written down you can easily transform pseudo code to any programming language. Allow a customer to deposit or withdraw money from a bank account, and if a user elects to withdraw funds, ensure that sufficient monies exist. Pseudo code for this problem statement might look like the following.
This nested condition is said to belong to its parent condition, such that the nested condition will never be evaluated unless one of the parent conditional requirements is met.
In this case, the action must not equal the deposit for the nested condition to be evaluated. Also notice that for each algorithm implemented with pseudo code, I use a standard form of indentation to improve the readability. Take a look at the same pseudo code; this time without the use of indentation. Without indentation in your pseudo code or actual program code, it is extremely difficult to pinpoint nested conditions.
In the next section, you will learn how to implement the same algorithms, shown previously, with flowcharts. Flowcharts Popular among computing analysts, flowcharts use graphical symbols to depict an algorithm or program flow. To demonstrate flowchart techniques, take another look at the AC algorithm used in the previous section.
The flowchart in Figure 3. If the expression evaluates to true, program flow moves to the right, processes a statement, and then terminates. If the expression evaluates to false, program flow moves to the left, processes a different statement, and then terminates. However, there are times when you will not care if an expression evaluates to false.
For example, take a look at the following algorithm implemented in pseudo code. C is a language that is as popular today as it was decades ago. C covers a wide variety of domains. It can be used to program a microcontroller, or to develop an entire operating system.
This book is an effort to introduce the reader to the C programming language in a concise and easy to follow manner. The author takes you through the C programming language, the Standard Library, and the C standards basics.
Each chapter is the right balance of theory and code examples. After reading and using this book, you'll have the essentials to start programming in modern C. Author : Harry. This C Programming book gives a good start and complete introduction for C Programming for Beginner's. Learn the all basics and advanced features of C programming in no time from Bestselling Programming Author Harry. All what you need!
Isn't it? Write powerful C programs See Below List Who knew how simple C programming could be? This is today's best beginner's guide to writing C programs-and to learning skills you can use with practically any language.
Its simple, practical instructions will help you start creating useful, reliable C code. You'll learn everything from the fundamentals to advanced topics. If you've read this book, you know what to expect a visually rich format designed for the way your brain works. If you haven't, you're in for a treat.
You'll see why people say it's unlike any other C book you've ever read. Learning a new language is no easy. You might think the problem is your brain. It seems to have a mind of its own, a mind that doesn't always want to take in the dry, technical stuff you're forced to study.
The fact is your brain craves novelty. It's constantly searching, scanning, waiting for something unusual to happen. After all, that's the way it was built to help you stay alive. It takes all the routine, ordinary, dull stuff and filters it to the background so it won't interfere with your brain's real work--recording things that matter. How does your brain know what matters? E Learn Complete C- without fear,.
Inside Chapters. Preface - Page-6, Introduction to C. Elements of C Programming Language. Control statements conditions. Control statements Looping. One dimensional Array. Multi-Dimensional Array. String Character Array. Every line she touches is improved by orders of magnitude. More important, computer games are a wonderful way to learn how to program because they teach you how to display an interface on a monitor, how to receive commands from the user, and how to manipulate information.
Ultimately, games are a blend of art and science that taps into logical and creative minds, providing stimulating visual, audio, and mental experiences for programmers and users. These common programming techniques will make it easier for you to learn how to program in other languages and create applications other than game applications. If you are an absolute beginner at programming, we suggest that you go through the chapters in their natural order. On the other hand, if you already have some experience in programming, you might want to gloss over the first six chapters, which cover the basics, and jump ahead to more advanced topics.
The book is conceptually, though not physically, organized into four sections. Because of the sequence of the topics in these chapters, we suggest going through them in order. You can cover these chapters in any order and fully comprehend them. The more you program, the better you will become at problem-solving an important skill in programming, as you will discover and detecting errors in your code.
Who knows, if you program enough, you might even be able to calculate pi to a million digits. Throughout the chapters, you will find small bits of code that illustrate concepts we present. At the end of each chapter, you will find a complete game that demonstrates the key ideas in the chapter, a summary of the chapter, and a set of challenges that tests your newfound knowledge.
We hope that you will try the games and challenges because they will really help you develop the feeling of programming. The solutions to the challenges are in Appendix A. However, we strongly encourage you to try the challenges before looking at the solutions even if you need help. They are all fairly short, so you can type them into your compiler which is, again, a good way to gain experience. Alert you to pitfalls to avoid.
Tips that will make programming easier and more efficient. We designed this chapter so that you can get your feet wet without having to delve into the deeper complexities of programming.
The chapter begins with a discussion on computers. The chapter continues with the basics on creating a program. Then you get to play with some text and numbers. With our help, and your ingenuity, you will soon be creating your own simple programs.
Here and now, your adventure begins! Some are very easy to identify: the keyboard, mouse, or the monitor. Others are internal and hidden to the novice user. These include the CPU central processing unit and the memory.
The CPU is the brain of the computer. It is the circuit-drenched core from which all decisions are made. If your computer one day decided to go all zombie on you and you needed to know where to stab, this would be the part to aim for.
And thus, the foul beast would return to the underworld from whence it came! The next most important component is the memory. Often called RAM random-access memory , this is where the data and instructions are stored. Data and instructions? Well, data can refer to many things. Keyboard input, file contents, web server requests, any piece of information that is used by the computer.
Instructions are a special kind of data. Add these two numbers, move this data here, jump to this instruction next. These are examples of CPU instructions. The main operation of the computer is executing these instructions. Fetch the next instruction. Execute it. Over and over again.
Except this all happens very fast. Special languages, called programming languages, have been developed that allow ideas to be expressed much more easily. It is up to an intermediate program, called a compiler, to translate ideas written in a programming language into a series of simple instructions that the computer can understand.
HIN T You may wonder why you cannot just tell the computer what to do. Even so, well-written code can be almost as easy to read as English.
And, just like English, grammar and punctuation is not all there is to it. In order to write good code, one must express his ideas succinctly and elegantly.
This is an art that programmers continually refine. Professional programmers who have been working in the field for years are still working to improve their coding abilities. But, enough talk. Though you may be overwhelmed at first with the odd symbols and cryptic terms, it will all become clear in time. So ready your torch and let us delve into this dark cavern!
But do not lose hope! By the end of the chapter, this code will seem perfectly natural. So, studious reader, the first thing you should do is compile and run this code to see exactly what it does. The running program is shown in Figure This function has no arguments and a void return value. All the code in this program is contained within this one function, and that code can be split into three parts: initialization, the main loop, and cleanup.
The initialization is the longest of the three sections. These two lines of code set the maximum frame rate. With a graphical computer game, it is important to control the rate at which things happen, because on modern computers things can become way too fast if they simply run as fast as possible.
The frame rate here is set to This means that the image on the screen will be updated 60 times every second at most. By default, a Dark GDK program will respond to the escape key by immediately quitting. Just like you use srand to seed the standard library random generator, you used dbRandomize to seed the Dark GDK random number generator.
Using dbTimer as a seed value is just like using time. Now we get to the exciting part! The call to dbLoadImage reads the background from an image file to get it ready to be displayed. This function takes two arguments: the filename of the image, and an id number that you assign.
You must remember this number so that you can refer to the loaded image in later code. A sprite in Dark GDK is a two-dimensional image that can be displayed on the screen. When we create a sprite, we give it an id and a position. The position refers to the top-left corner of the image and, since this is a background for the whole screen, is set to the top-left corner of the screen, or 0,0.
The image id is used as the fourth parameter to refer to the previously loaded image file. Using the dbSetImageColorKey function, you can make a certain color be displayed as transparent onscreen. This can be a convenient way to convert a square image file into, say, an asteroid shaped image onscreen. The last step is to create the 28 asteroid sprites at random locations. These sprites are different from the background in that they are animated. Take a look at Figure As you can see, all the different frames of animation are stored in the same file.
You must provide the number of animation frames per row and the number of columns. Even though the sprite is created with this function call, we must still call dbSprite to give this sprite a position.
All of the code included in this loop is executed once per frame. The first thing done in the main loop is to loop through all of the asteroid sprites and move them down. This is accomplished with the dbMoveSprite function. Also, the dbPlaySprite function is used to automatically cycle through all of the animation frames at a rate of 60 frames per second. When a particular asteroid sprite has gone past the bottom of the screen, its position is reset to a new random location.
Every frame, dbEscapeKey is used to check if the escape key has been pressed. If it has, we break out of the main loop, effectively ending the program.
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