calculator in c

1#include <stdio.h>
2int main() {
3    char operator;
4    double first, second;
5    printf("Enter an operator (+, -, *,): ");
6    scanf("%c", &operator);
7    printf("Enter two operands: ");
8    scanf("%lf %lf", &first, &second);
9
10    switch (operator) {
11    case '+':
12        printf("%.1lf + %.1lf = %.1lf", first, second, first + second);
13        break;
14    case '-':
15        printf("%.1lf - %.1lf = %.1lf", first, second, first - second);
16        break;
17    case '*':
18        printf("%.1lf * %.1lf = %.1lf", first, second, first * second);
19        break;
20    case '/':
21        printf("%.1lf / %.1lf = %.1lf", first, second, first / second);
22        break;
23        // operator doesn't match any case constant
24    default:
25        printf("Error! operator is not correct");
26    }
27
28    return 0;
29}

1#include <stdio.h>
2//Simple Calculator
3int main() {
4
5        int fno;
6        int sno;
7        int rst;
8       char opr;
9       printf ( "Enter First Number: ");
10       scanf("%d", &fno);
11       printf ("Enter Second Number: ");
12       scanf("%d", &sno);
13       printf ("Type Operator : ");
14       scanf(" %c", &opr);
15       rst = fno + sno;
16    if (opr == '+')
17    
18        printf ("%d \n", fno+sno);
19    
20      else (opr == '-');
21        printf ("%d \n", fno-sno);
22
23    if (opr == '*')
24    
25        printf("%d \n", fno*sno);
26
27      else (opr == '/');
28        printf ("%d \n", fno/sno);
29}
30
31

1/*C program to design calculator with basic operations using switch.*/
2 
3#include <stdio.h>
4 
5int main()
6{
7    int num1,num2;
8    float result;
9    char ch;    //to store operator choice
10     
11    printf("Enter first number: ");
12    scanf("%d",&num1);
13    printf("Enter second number: ");
14    scanf("%d",&num2);
15     
16    printf("Choose operation to perform (+,-,*,/,%): ");
17    scanf(" %c",&ch);
18     
19    result=0;
20    switch(ch)    
21    {
22        case '+':
23            result=num1+num2;
24            break;
25             
26        case '-':
27            result=num1-num2;
28            break;
29         
30        case '*':
31            result=num1*num2;
32            break;
33             
34        case '/':
35            result=(float)num1/(float)num2;
36            break;
37             
38        case '%':
39            result=num1%num2;
40            break;
41        default:
42            printf("Invalid operation.\n");
43    }
44 
45    printf("Result: %d %c %d = %f\n",num1,ch,num2,result);
46    return 0;
47}