C Programming Basics – C Language Tutorial For Beginners

c programming basicsC is a high level, general purpose programming language initially developed by Dennis Ritchie in 1972 for the Unix operating system. The Unix operating system and most Unix applications are written in C and today is still one of the most widely used programming languages around. In fact C is so popular that most modern languages have either directly or indirectly borrowed from C in one way or another. Languages based on C or C syntax include Java, JavaScript, C#, Objective-C, PHP and Python. Learning to program in C can therefore serve as a great base for learning other programming languages. If you would like to learn the basics of C, then sign up for the C Programming For Beginners course. This course is designed to teach beginners how to program in C as well as teaching students who are familiar with languages line Java, Ruby or Python. The course includes lessons on the fundamentals of programming and how to program on both Mac and Windows. The course includes the details of C and includes advanced topics like memory allocation, the stack and heap and binary file IO.

Here are some C programming basics for those new to programming in C.

C Program Basics

All C programs basically contain the following elements:

1.       Preprocessor Commands

2.       Functions

3.       Variables

4.       Statements and Expressions

5.       Comments

Preprocessor Commands

These commands tell the processor to do something before compilation. Preprocessor commands generally consist of include statements. The include command is called using the hash key and these statements tell C to include the contents of the included file before it continues on to process the rest of the commands.

The following is an example of a preprocessor command:

#include <stdio.h>

This command tells C to include the functions within the stdio.h file before it moves onto the next function and compiles the functions within this program. The stdio.h file includes functions like the printf and getchar functions so these functions are loaded and ready for use by using the include directive.

Functions

C programs mainly consist of functions and functions form the main building blocks of a C program. Every C program must contain at least one function called “main()”. The main function returns a variable and is therefore prefaced by the keyword “int” to represent the integer it returns. The integer is returned in the function using the return keyword. Functions are delineated using curly brackets. Each set of brackets marks a function. Curly braces are used to delineate code blocks within the C programming environment.

Here is a very basic example of a C program:

#include <stdio.h>
int main()
{
/* My first C program */
printf("I can program in C! \n");
return 0;
}

Note the inclusion of the stdio.h file so that we can access the printf function and note the curly brackets to show that this is a single code block. The stdio file is an acronym for “standard input/output” and hence contains a lot of the input/output functions used in C like the printf, getchar, and scanf functions.

Variables in C

Like most programming languages, C allows for the declaration of variables. There are two types of variables recognized by C namely, local and global variables. Variables are declared by declaring the variable type and assigning a name to the variable. Variable type can include int which stores an integer, char which stores a single char, float which stores floating point values and pointer which stores the address of another variable.

Local variables have a limited scope. Their scope is limited to the duration of the programming block within which the variable is defined. Local variables are declared at the top of the programming block to which they apply. A local variable must be initialized by the programmer. The variable is no longer available when the programming block has completed. Each variable name must be unique but a function can have more than one type of variable declared for that function.

Global variables must be declared at the start of the program. It is visible throughout the program and can be modified by any function within the program. Global variables are automatically initialized by the system and have the following values, unless other values are assigned by the programmer. Integers are initialized with a value of 0, char are initialized with a value of ‘’, float variables are automatically initialized with a value of 0 and pointers are automatically initialized with a value of “NULL”.

Take a look at the following code to see how global and local variables work:

main()

{

int x = 4;       /* Declare global variable x = 4

int a = 10;      /* Declare global variable a = 10

 

x++;             /* increment x by one for each loop

 

if (a > 0)

{

/* no local variable x so global variable applies */

printf("x is %d\n",x);       /* print value of x */

}

 

if (a > 0)

{

/* local variable called x applies so global variable ignored */

int x=100;

printf("x is %d\n",x);     /* print value of x */

}/* the local value of x is released here */

 

printf("x is %d\n",x);   /* x refers to the global variable again */

}

 

This will generate following output

x is 5

x is 100

x is 5

In the above example, you can see that a global variable called x is created and initialized with a value of 4. X is then incremented by one so the global variable x is equal to 5. The first if statement does not declare x so the printf statement results in an output of x as 5. The next if statement includes the declaration of a local variable called x with a value of 100. The printf function therefore results in x being given a value of 100. This local variable only applies to this code block so as soon as the code block ends the value of the local variable is released so now we return to the global variable of x which still equals 5.

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Statements and Expressions

A C program also generally contains statements and expressions. Statements and expressions allow programmers to use variables in combination with various predefined programming structures like statements or expressions to create useful code. Statements and expressions include control statements like the IF statement and switch statements, programming loops like For and While loops. Each expression has unique syntax and expression requirements depending on the expression or statement the programmer uses.

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Comments

Finally, like most programming languages, C programs will most likely contain comments. Comments in C are delineated using the “/*…*/” notation. Comments can be single or multiple line comments.

Comments are an important part of every program. Comments are there to help to explain the function of the code. There are a number of best practices with regards to commenting within a program but comments should at the very least explain the rationale behind the statements and functions used within the code. Comments should explain the purpose of the code without explaining the language itself. Comments should be consistent in form and consistent in notation. Comments are there in case other programmers need to work on your code. It is also important to update comments if you are updating the code.

Learn C Programming Basics and Start Programming In C Today

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