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# Calculator Program in C (3 Examples)

Below are the 3 examples of calculator programs in the C language.

## Example 1:

In the following C program example, it will first ask the user to input an operand (+, -Â  or *) and then will ask for the two numbers and then will give the calculated value:

```#include
int main() {
char operator;
double first, second;
printf("Enter an operator (+, -, *,): ");
scanf("%c", &operator);
printf("Enter two operands: ");
scanf("%lf %lf", &first, &second);

switch (operator) {
case '+':
printf("%.1lf + %.1lf = %.1lf", first, second, first + second);
break;
case '-':
printf("%.1lf - %.1lf = %.1lf", first, second, first - second);
break;
case '*':
printf("%.1lf * %.1lf = %.1lf", first, second, first * second);
break;
case '/':
printf("%.1lf / %.1lf = %.1lf", first, second, first / second);
break;
default:
printf("Error! operator is not correct");
}

return 0;
}
```

### Output:

```Enter an operator (+, -, *,): +
Enter two operands: 2 4
2.0 + 4.0 = 6.0```

## Example 2:

In the following C program, first, it will ask the user to enter the first number and then the second number, and then the operator:

```#include
//Simple Calculator
int main() {

int fno;
int sno;
int rst;
char opr;
printf ( "Enter First Number: ");
scanf("%d", &fno);
printf ("Enter Second Number: ");
scanf("%d", &sno);
printf ("Type Operator : ");
scanf(" %c", &opr);
rst = fno + sno;
if (opr == '+')

printf ("%d \n", fno+sno);

else (opr == '-');
printf ("%d \n", fno-sno);

if (opr == '*')

printf("%d \n", fno*sno);

else (opr == '/');
printf ("%d \n", fno/sno);
}
```

### Output:

```Enter First Number: 5
Enter Second Number: 3
Type Operator : *
2
15
1```

## Example 3:

The following C program uses the same input logic as above but having a different program logic:

```#include

int main()
{
int num1,num2;
float result;
char ch;    //to store operator choice

printf("Enter first number: ");
scanf("%d",&num1);
printf("Enter second number: ");
scanf("%d",&num2);

printf("Choose operation to perform (+,-,*,/,%): ");
scanf(" %c",&ch);

result=0;
switch(ch)
{
case '+':
result=num1+num2;
break;

case '-':
result=num1-num2;
break;

case '*':
result=num1*num2;
break;

case '/':
result=(float)num1/(float)num2;
break;

case '%':
result=num1%num2;
break;
default:
printf("Invalid operation.\n");
}

printf("Result: %d %c %d = %f\n",num1,ch,num2,result);
return 0;
}
```

### Output:

```Enter first number: 4
Enter second number: 2
Choose operation to perform (+,-,*,/,%): -
Result: 4 - 2 = 2.000000```