|C - Programming

|C - PROGRAMMING

C PROGRAMMING -Preprocessors- #define, #include

#define:

 In the C Programming Language, the #define directive allows the definition of macros within your source code.

 These macro definitions allow constant values to be declared for use throughout your code.

 This macro defines constant value and can be any of the basic data types.

Syntax:

#define CNAME value Or #define CNAME (expression)

Syntax Explanation:

 CNAME: CNAME is specified as a name of the constant. Most C programmers define their constant names in uppercase, but it is not a requirement of the C Language.

 Value: value is represented as the value of the constant.  Expression: Expression whose value is assigned to the constant. The expression must be enclosed in parentheses if it contains operators.

#include:

 In the C Programming Language, the #include directive tells the preprocessor to insert the contents of another file into the source code at the point where the #include directive is found.

 Include directives are typically used to include the C header files for

C functions that are held outsite of the current source file.

 The source code of the file “file_name” is included in the main C program where “#include ” is mentioned.

Syntax:

#include Or #include "header_file"

 header_file: The name of the header file that you wish to

include.

 A header file is a C file that typically ends in ".h" and contains declarations and macro definitions which can be shared between several source files.

Sample Code:

#include #include

#define NAME "www.wikitechy.com"

#define AGE 20 void main() { clrscr(); printf("%s is website", NAME); printf("\n"); printf(" %d years old", AGE); getch(); }

Code Explanation:

In C programming #include specifies is a statement

which tells the compiler to insert the contents of stdio at that particular place. A header file is a C file, that typically ends in ".h".

In this example, #define NAME “www.wikitechy.com” specifies the

constant called NAME would contain the value of

“www.wikitechy.com”.

In this example, “#define AGE 20” specifies the constant

called AGE would contain the value of “20”. Sample Output:

Here in this output “www.wikitechy.com is website” represents the

constant called NAME would contain #define directive NAME.

Here in this output the statement “20 years old.” represents the

constant called AGE would contain #define directive AGE.