unknown type name, expected identifier in c

Question

Here is my program:

#include <stdio.h>

int main() {
    int menunum;
    int operand1, operand2;
    printf("Select number 1: ");
    scanf("%d", operand1);
    printf("Select number 2: ");
    scanf("%d", operand2);
    
    printf("Select operation: \n");
    printf("(1) add(+)\t(2) sub(-)\n");
    scanf("%d", &menunum);
    
    switch (menunum) {
      case 1:
        printf("Result: %d+%d=%d", operand1, operand2, operand1 + operand2);
        break;
      case 2:
        printf("Result: %d-%d=%d", operand1, operand2, operand1 - operand2);
        break;
    }

When I run the compiler, I get this error:

test.c:1:1: error: unknown type name 's'
s
^
test.c:1:2: error: expected identifier or '('
s
 ^
2 errors generated.

please help me

Answer 1

Check first and second scanf of your code you have missed Ampersand (&) before operand1 and operand2 and also add a close curly bracket for your main function.

scanf("%d", &operand1);
scanf("%d", &operand2);

Note The ampersand (&) allows us to pass the address of variable number which is the place in memory where we store the information that scanf read.

Updated Code

#include <stdio.h>

int main(){
    int menunum;
    int operand1, operand2;
    printf("Select number 1: ");
    scanf("%d", &operand1);
    printf("Select number 2: ");
    scanf("%d", &operand2);

    printf("Select operation: \n");
    printf("(1) add(+)\t(2) sub(-)\n");
    scanf("%d", &menunum);

    switch(menunum) {
        case 1:
            printf("Result: %d+%d=%d", operand1, operand2, operand1+operand2);
            break;
        case 2:
            printf("Result: %d-%d=%d", operand1, operand2, operand1 - operand2);
        break;

    }
}