C Calculator program not performing operations correctly

I am a bare bones beginner, so there definitely could be something obvious I'm missing, but for some reason this code keeps outputting the first variable instead of the sum, subtraction, etc.

#include <stdio.h>
int main(){
    int numone=0, numtwo=0;
    char sign;
    printf("Please enter the first number: ");
    scanf("%d", &numone);
    printf("Please enter the second number: ");
    scanf("%d", &numtwo);
    printf("Please enter the operation: ");
    scanf("%s", &sign);
    switch (sign) {
        case '+':
            printf("The result is: %d", numone + numtwo);
            break;
        case '-':
            printf("The result is: %d", numone - numtwo);
            break;
        case '*':
            printf("The result is: %d", numone * numtwo);
            break;
        case '/':
            printf("The result is: %d", numone / numtwo);
            break;
        default:
            printf("Error! operator is not correct");
    }
    return 0;
}

%s in scanf() expects a multi-byte buffer for input chars and null terminator, but &sign points to a single byte. You definitely wanted to read a single char and should have used %c. Try this

scanf(" %c", &sign)

Note the space prior %c, it lets us skip whitespaces before a significant character.