How to take in multiple inputs using linux to do operations

Question

I need help understanding why code isn't working. I don't have a full understanding how to use argc and argv. I need to do addition, subtraction, multiplication, and division operations that can have multiple inputs. The addition is adding them all together, i was able to get that one. For the others, its taking the first input and either subtracting/dividing/multiplying by the rest. I'm using linux. To input the numbers, i would do (./.a.out 1 2 3 4) to input integers. Thank you

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

int main( int argc, const char * argv[])
{
    float sum=0.0;
    float sub=0.0;
    float div=0.0;
    float mult=0.0;

    char ch;

    printf("Pick a function \n");
    scanf("%c", &ch);  

    int x,y;

    switch(ch)                                                        
    {
    case ('A'):                                                           
        {
        x = argc -1;
        for(y=0;y<x;y++)
        {
        sum = sum + atoi(argv[y+1]);
        }
        printf("The result of addition is %f\n",sum);             
        break;
        }
    case ('S'):
        {
        x = argc -1;
        for(y=0;y<x;y++)
        {
        sub = sub - atoi(argv[y+1]);
        }
        printf("The result of subtraction is %f\n",sub);             
        break;
        }
    case ('M'):
        {
        x = argc -1;
        for(y=0;y<x;y++)
        {
        mult = mult * atoi(argv[y+1]);
        }
        printf("The result of multiplication is %f\n",mult);              
        break;
        }
    case ('D'):
        {
        x = argc -1;
        for(y=0;y<x;y++)
        {
        div = div / atoi(argv[y+1]);
        }
        printf("The result of division is %f\n",div);              
        break;
        }
    }
}

Answer 1

Here's the blueprint of what you need to fix:

    #include <iostream>
    // etc..
    using namespace std;

    float mult = 1.0;
    float div = 1.0;

    case ('M'):
    {
            x = argc - 1;
            for (int y = 0; y < x; ++y)
            {
                mult = mult * atoi(argv[y+1]);
            }
            cout << "The result of multiplication is" << mult << endl;             
            break;
    }

For subtraction and division, just have sub = atoi(argv[1]); / div = atoi(argv[1]); outside of the loop, and set loop control variable to int y = 1 for both.