Functions
Function definition:int square(int a) { return(a*a);}
Function declaration:int square(int); /* prototype */A function must be declared before use.
A function can be declared via a prototypebefore it is actually defined.
Prototype: - the function name- type of return value- type of arguments
Example:int square(int);main() { int x,y=2; x = square(y); /* A function call */ printf(“square of %d is %d\n”,y,x); }