Use of function in mathematics

 // nested function (a program to display some messages in sub() and nest()

#include<stdio.h>

void main()

{

    void sub();

    printf("\nthis is my destiny");

    sub();

    printf("\nthis is also my destiny");

}

void sub()

{

    void nest();

    printf("\nthis is the love");

    nest();

    printf("\nthis is what i really want");

}

void nest()

{

    void love();

    

    printf("\nthis is the real love");

    

    

}