C Program to Create Simple Calculator

How to write a C Program to Create a Simple Calculator using Switch case, Functions, and Else If Statement.

This calculator program helps the user to enter the Operator (+, -, *, or /) and two values. Using those two values and operand, it will perform Arithmetic Operations.

For this calculator program example, we used the Switch case to check which operand is inserted by the user. Next, based on the Operand result will be displayed.

 #include <stdio.h>
 
int main()
{
	char Operator;
	float num1, num2, result = 0;
	
	printf("\n Please Enter an Operator (+, -, *, /)  :  ");
  	scanf("%c", &Operator);
  	
	printf("\n Please Enter the Values for two Operands: num1 and num2  :  ");
  	scanf("%f%f", &num1, &num2);
  	
  	switch(Operator)
  	{
  		case '+':
  			result = num1 + num2;
  			break;
  		case '-':
  			result = num1 - num2;
  			break;  			
  		case '*':
  			result = num1 * num2;
  			break;
  		case '/':
  			result = num1 / num2;
  			break;
		default:
			printf("\n You have enetered an Invalid Operator ");				    			
	}
  
	printf("\n The result of %.2f %c %.2f  = %.2f", num1, Operator, num2, result);
	
  	return 0;
}

C Program to Create Simple Calculator Example 2

It is the same C program that we used in the first example. But this time, we are performing the arithmetic operation directly inside the Switch case blocks.

#include <stdio.h>
 
int main()
{
	char Operator;
	float num1, num2, result = 0;
	
	printf("\n Please Enter an Operator (+, -, *, /)  :  ");
  	scanf("%c", &Operator);
  	
	printf("\n Please Enter the Values for two Operands: num1 and num2  :  ");
  	scanf("%f%f", &num1, &num2);
  	
  	switch(Operator)
  	{
  		case '+':
  			printf("\n The result of %.2f + %.2f  = %.2f", num1, num2, num1 + num2);
  			break;
  		case '-':
  			printf("\n The result of %.2f - %.2f  = %.2f", num1, num2, num1 - num2);
  			break;  			
  		case '*':
  			printf("\n The result of %.2f * %.2f  = %.2f", num1, num2, num1 * num2);
  			break;
  		case '/':
  			printf("\n The result of %.2f / %.2f  = %.2f", num1, num2, num1 / num2);
  			break;
		default:
			printf("\n You have enetered an Invalid Operator ");				    			
	}
	
  	return 0;
}

 Please Enter an Operator (+, -, *, /)  :  +

 Please Enter the Values for two Operands: num1 and num2  :  125 179

 The result of 125.00 + 179.00  = 304.00P

Program to Create Simple Calculator using else if

In this example, we are using the Else If Statement to create a simple calculator in c.

#include <stdio.h>
 
int main()
{
	char Operator;
	float num1, num2, result = 0;
	
	printf("\n Please Enter an Operator (+, -, *, /)  :  ");
  	scanf("%c", &Operator);
  	
	printf("\n Please Enter the Values for two Operands: num1 and num2  :  ");
  	scanf("%f%f", &num1, &num2);
  	
  	if(Operator == '+')
  	{
  		printf("\n The result of %.2f + %.2f  = %.2f", num1, num2, num1 + num2);
  	}
  	else if(Operator == '-')
  	{
  		printf("\n The result of %.2f - %.2f  = %.2f", num1, num2, num1 - num2);
  	}
  	else if(Operator == '*')
  	{
  		printf("\n The result of %.2f * %.2f  = %.2f", num1, num2, num1 * num2);
  	}
  	else if(Operator == '/')
  	{
  		printf("\n The result of %.2f / %.2f  = %.2f", num1, num2, num1 / num2);
  	}
  	else
  	{
  		printf("\n You have enetered an Invalid Operator ");
	}
	
  	return 0;
}

 Please Enter an Operator (+, -, *, /)  :  /

 Please Enter the Values for two Operands: num1 and num2  :  1465 32

 The result of 1465.00 / 32.00  = 45.78

Program to Create Simple Calculator using functions

It is the same calculator program that we used in the first example. However, we separated the C Programming arithmetic operations logic using Functions.

#include <stdio.h>
float add(float a, float b);
float sub(float a, float b);
float multi(float a, float b);
float divi(float a, float b);

int main()
{
	char Operator;
	float num1, num2, result = 0;
	
	printf("\n Please Enter an Operator (+, -, *, /)  :  ");
  	scanf("%c", &Operator);
  	
	printf("\n Please Enter the Values for two Operands: num1 and num2  :  ");
  	scanf("%f%f", &num1, &num2);
  	
  	switch(Operator)
  	{
  		case '+':
  			result = add(num1, num2);
  			break;
  		case '-':
  			result = sub(num1, num2);
  			break;  			
  		case '*':
  			result = multi(num1, num2);
  			break;
  		case '/':
  			result = divi(num1, num2);
  			break;
		default:
			printf("\n You have enetered an Invalid Operator ");				    			
	}
  
	printf("\n The result of %.2f %c %.2f  = %.2f", num1, Operator, num2, result);
	
  	return 0;
}

float add(float a, float b)
{
	return a + b;
}

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

float multi(float a, float b)
{
	return a * b;
}

float divi(float a, float b)
{
	return a / b;
}

 Please Enter an Operator (+, -, *, /)  :  -

 Please Enter the Values for two Operands: num1 and num2  :  1462 2932.85

 The result of 1462.00 - 2932.85  = -1470.85