Constant qualifiers can be declared with keyword const. An object declared by const cannot be modified.
const int p=20;
The value of p cannot be changed in the program.
Volatile qualifiers:
A variable should be declared volatile whenever its value can be changed by some external sources outside program. Keyword volatile is used to indicate volatile variable.
C Programming Input Output (I/O)
ANSI standard has defined many library functions for input and output in C language. Functions printf() and scanf() are the most commonly used to display out and take input respectively. Let us consider an example:
#include <stdio.h> //This is needed to run printf() function.
int main()
{
printf("C Programming"); //displays the content inside quotation
return 0;
}