A program for custom function : calculator

See below code i have created a calculator with the use of my own custom functions.

Here you can learn : how to create custom functions in C?

C - Code Example #include<stdio.h> #include<conio.h> void sum(int,int); // Function prototype declaration. void product(int,int); // Function prototype declaration. void substraction(int,int); // Function prototype declaration. void divide(int,int); // Function prototype declaration. void sum(int x,int y) // Definition function. { int z; z=x+y; printf("%d + %d = %d\n", x,y,z); } void product(int x,int y) // Definition function. { int z; z=x*y; printf("%d x %d = %d\n", x,y,z); } void substraction(int x,int y) // Definition function. { int z; z=x-y; printf("%d - %d = %d\n", x,y,z); } void divide(int x,int y) // Definition function. { float z; z=x/y; printf("%d / %d = %f\n", x,y,z); } void main() { int a,b,i; clrscr(); printf("\n\n***********Calculator : Type number***********\n\n"); printf("Type first number : "); scanf("%d",&a); printf("\nType second number : "); scanf("%d",&b); clrscr(); printf("\n\n***********Calculator : Choose operation***********\n\n"); printf("Select an option for perform the calculation task for these two numbers %d and %d\n\n",a,b); printf("Choose option \n\n"); printf("for \n'+' : (1)'\n'x' : (2)\n'-' : (3)\n'/' : (4) : "); printf("\n\nType here : "); scanf("%d",&i); clrscr(); printf("\n\n***********Calculator : Result (%d and %d)***********\n\n",a,b); printf("Results is : "); switch(i) { case 1 : sum(a,b);break; // Calling function. case 2 : product(a,b);break; // Calling function. case 3 : substraction(a,b);break; // Calling function. case 4 : divide(a,b);break; // Calling function. default : printf("\nYou put invalid input!!!"); // Calling function. break; } printf("\n\n***********Thanks for using it***********\n\n"); printf("\n\n\n\n\t\t\t\tCreated by : Pawan Mall"); getch(); } Download file : Calculator