为什么我的代码只返回一个函数？

Question

I am new to Programming (starting with C), and tried to practice functions by building a calculator. But it only ever returns me the same function even though its If-Statement is not being called. This is my code:

#include <stdio.h>
#include <stdlib.h>

int result;
int multiplication(int num1, int num2){

    result = num1 * num2;
    return result;
};

int addition(int num1, int num2){

    result = num1 + num2;
    return result;
};

int substraction(int num1, int num2){

    result = num1 - num2;
    return result;
};

int main(){
    int num1;
    int num2;
    char Math;

    printf("Do you want to do a Multiplication or an Addition, or a Substraction: ");
    scanf("%c", &Math);
    printf("Now give me a Number: ");
    scanf("%d",&num1);
    printf("Now give me another Number: ");
    scanf("%d",&num2);

    if(Math = 'M' || 'm'){
        printf("Your Mulitplication came out to %d", multiplication(num1,num2));
}
    else if(Math = 'A' || 'a'){
        printf("Your Addition came out to %d", addition(num1, num2));
}
    else if(Math = 'S' || 's'){
        printf("Your Substraction came out to %d", substraction(num1, num2));
}
    else{
        printf("Your Input was wrong");
};

return 0;



}

I would really appreciate every bit of advice i can get!

Answer 1

This here

if(Math = 'M' || 'm')

Needs to be changed to

if((Math == 'M') || (Math == 'm'))

Because as it is, 'M' || 'm' 'M' || 'm' just turns into 1 , which is then assigned to Math , and that result is returned, which means the if is taken. With this change, you're actually comparing Math to 'M' , and if it's not equal, to 'm' .

Likewise for else if(Math = 'A' || 'a') and so on.

Answer 2

note (=) is diffrent from (==)

= is assignment operator it assigns the value in your code you are assigning the value 'M' to Math and logical operators return either 0 or 1. in this case, it returns 1 since 1 is returned control flows inside if and the result of the multiplication is obtained as output