C Language Tutorials by Ghulam Murtaza Dahar - HTML preview

Output

4 day

You can write any program in C language without the help of enumerations but, enumerations helps in writing clear codes and simplify programming.

C Programming Preprocessor and Macros

Preprocessor extends the power of C programming language. Line that begin with # are called preprocessing directives.

Use of #include

Let us consider very common preprocessing directive as below:

#include <stdio.h>

Here, "stdio.h" is a header file and the preprocessor replace the above line with the contents of header file.

Use of #define

Preprocessing directive #define has two forms. The first form is:

#define identifier token_string

token_string part is optional but, are used almost every time in program.

Example of #define

#define c 299792458 /*speed of light in m/s */

The token string in above line 2299792458 is replaced in every occurance of symbolic constant c.

C Program to find area of a cricle. [Area of circle=πr2]

#include <stdio.h>

#define PI 3.1415

int main(){

int radius;

float area;

printf("Enter the radius: ");

scanf("%d",&radius);

area=PI*radius*radius;

printf("Area=%.2f",area);

return 0;

}