// CALCULATOR
#include<stdio.h>
// return_type function_name(input_type,input_type,.......); declaring function/function prototype
float add(float , float );
float sub(float , float ); 
float multiply(float , float );
float divide(float ,float );

int main()	{	
  float num1,num2;
  int choice,loop;
  printf ("\n Enter 1:Add 2:Subtract 3:Multiply 4:Divide 5:Exit ");
  while(loop=1)	{
	scanf("%d ", &choice);
 	if(choice==1)	{
		puts("Enter The Two Number ");
		scanf("%f",&num1);
		scanf("%f",&num2);
		printf(  "%f + %f =%f  ",num1,num2,add(num1,num2)  );
			}

 	if(choice==2)	{
		puts("Enter The Two Number ");
		scanf("%f ",&num1);
		scanf("%f",&num2);
		printf(  "%f - %f =%f ",num1,num2,sub(num1,num2)  );
			}

 	if(choice==3)	{
		puts("Enter The Two Number ");
		scanf("%f",&num1);
		scanf("%f",&num2);
		printf(  "%f x %f =%f ",num1,num2,multiply(num1,num2)  );
			}
	
 	if(choice==4)	{
		puts("Enter The Two Number ");
		scanf("%f",&num1);	
		scanf("%f",&num2);
		printf(  "%f / %f =%f  ",num1,num2,divide(num1,num2)  );
			}
	if(choice==5){
		loop=0;
		break;}
	}
}

float add(float num1,float num2)// as num 1 and num2 are not global variable 
/*if you want you can give any name to the two number here not necessary to give same name used when calling 
variable just check the next line */
	{return num1+num2;}

float sub(float a,float b)	{ 
	return a-b;		}

float multiply(float num1,float num2)	{
	return num1*num2;		}

float divide (float num1 , float num2)	{
	return num1/num2;	}