## Q. Write a program to make a simple calculator.

Calculator :- A calculator is used to make mathematical calculations. In this program we will create a simple calculator that can perform an arithmetic operation (+, -, *, /).
For Example :-
Enter an operator (+, -, *, /): *
Enter two operands: 1.5 4.5
1.5 * 4.5 = 6.8
So as we can see that first we have to choose which arithmetic operation we want to do, then after selecting two operands for which we have to do arithmetic calculation.

## Calculator Program Algorithm

```START
Step 1 : Initialise the two numbers.
Step 2 : Ask the user to enter an option by giving six options.
Step 3 : After getting the option from the user write if conditions for every operation based on the option.
Step 4 : Perform the respective operation.
Step 5 : Print the result.
STOP
```

# Calculator Program

• C
• C++
• Java
• Python
• ```#include <stdio.h>
int main() {
char ch;
double num1, num2;
printf("Enter an operator (+, -, *, /): ");
scanf("%c", &ch);
printf("Enter two operands: ");
scanf("%lf %lf", &num1, &num2);
switch (ch) {
case '+':
printf("%.1lf + %.1lf = %.1lf", num1, num2, num1 + num2);
break;
case '-':
printf("%.1lf - %.1lf = %.1lf", num1, num2, num1 - num2);
break;
case '*':
printf("%.1lf * %.1lf = %.1lf", num1, num2, num1 * num2);
break;
case '/':
printf("%.1lf / %.1lf = %.1lf", num1, num2, num1 / num2);
break;
// operator doesn't match any case constant
default:
printf("Error! operator is not correct");
}
return 0;
}
```
```#include <bits/stdc++.h>
using namespace std;
int main()
{
char ch;
float num1, num2;
cout << "Enter an operator (+, -, *, /):  ";
cin >> ch;
cout << "Enter two operands: ";
cin >> num1 >> num2;
switch(ch)
{
case '+':
cout << num1+num2;
break;
case '-':
cout << num1-num2;
break;
case '*':
cout << num1*num2;
break;
case '/':
cout << num1/num2;
break;
default:
// If the operator is other than +, -, * or /, error message is shown
cout << "Error! operator is not correct";
break;
}
return 0;
}
```
```import java.util.Scanner;
public class LFC {
public static void main(String[] args) {
System.out.print("Enter two operands: ");
// nextDouble() reads the next double from the keyboard
System.out.print("Enter an operator (+, -, *, /):  ");
double res;
switch(ch)
{
case '+':
res = num1 + num2;
break;
case '-':
res = num1 - num2;
break;
case '*':
res = num1 * num2;
break;
case '/':
res = num1 / num2;
break;
// operator doesn't match any case constant (+, -, *, /)
default:
System.out.printf("Error! operator is not correct");
return;
}
System.out.printf("%.1f %c %.1f = %.1f", num1, ch, num2, res);
}
}```
```# Program make a simple calculator
# This function adds two numbers
return x + y
# This function subtracts two numbers
def subtract(x, y):
return x - y
# This function multiplies two numbers
def multiply(x, y):
return x * y
# This function divides two numbers
def divide(x, y):
return x / y
# Take input from the user
ch = input("Enter an operator (+, -, *, /): ")
num1 = float(input("Enter first number: "))
num2 = float(input("Enter second number: "))
if ch == '+':
elif ch == '-':
print(num1,"-",num2,"=", subtract(num1,num2))
elif ch == '*':
print(num1,"*",num2,"=", multiply(num1,num2))
elif ch == '/':
print(num1,"/",num2,"=", divide(num1,num2))
else:
print("Error! operator is not correct")
```
```#include <stdio.h>
int main() {
char ch;
double num1, num2;
printf("Enter an operator (+, -, *, /): ");
scanf("%c", &ch);
printf("Enter two operands: ");
scanf("%lf %lf", &num1, &num2);
switch (ch) {
case '+':
printf("%.1lf + %.1lf = %.1lf", num1, num2, num1 + num2);
break;
case '-':
printf("%.1lf - %.1lf = %.1lf", num1, num2, num1 - num2);
break;
case '*':
printf("%.1lf * %.1lf = %.1lf", num1, num2, num1 * num2);
break;
case '/':
printf("%.1lf / %.1lf = %.1lf", num1, num2, num1 / num2);
break;
// operator doesn't match any case constant
default:
printf("Error! operator is not correct");
}
return 0;
}
```

#### Output

```Enter an operator (+, -, *, /): *
Enter two operands: 8 6
8.0 * 6.0 = 48.0
```

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