Thread: Help Wanted for Simple C Arithmetic Calculator Involving getchar()

I've been stuck at a roadblock for almost an hour now. I'm trying to write a program that takes user input from the command prompt of the form:
[n # spaces] [operand] [n # spaces] [operator] [operand] [n#spaces]

Where each [n # spaces] component means some unknown number of spaces. For example, the user should be able to enter some expression such as: " 380 * 4 " and get both their output echoed and the result of the expression. We can only use getchar() to read input; no string handling functions are allowed. We can also assume the operands are positive integers. For now I believe these are the only relevant conditions of the problem necessary to share.

Initially I thought the program would be straightforward and to some extent it was; I got the echo to work up to and including the operator as well as the answer function to work, but after a few small changes I was foolish enough to not keep track of the program seems to hardly work at all. I had to quickly teach myself pointers because I wanted to circumvent the supposed fact that C cannot pass parameters to functions by reference like you can in C++, so I'm betting the problem lies there, but again all of my functions seem to have been working just a while ago.

Source Code:

Code:

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


//Prototypes
int SpaceCounts(int* iovar_p);
int Operand(int* iovar_p);
char Operator(int* iovar_p);
double answer(int operand1, int operand2, char Arsign);
void PrintSpaces(int spaces);


int main()
{
    int iovar = getchar();
    int spaces1, spaces2, spaces3, spaces4;
    char ArSign;
    int operand1, operand2;


    spaces1 = SpaceCounts(&iovar);
    printf("%d", spaces1);
    operand1 = Operand(&iovar);
    spaces2 = SpaceCounts(&iovar);
    ArSign = Operator(&iovar);
    spaces3 = SpaceCounts(&iovar);
    operand2 = Operand(&iovar);
    spaces4 = SpaceCounts(&iovar);


    //Output
    PrintSpaces(spaces1);
    printf("%d", operand1);
    PrintSpaces(spaces2);
    printf("%c", ArSign);
    PrintSpaces(spaces3);
    printf("%d", operand2);
    PrintSpaces(spaces4);
    printf("= ");
    printf("%6.2f", answer(operand1, operand2, ArSign));








    system("pause");
    return 0;
}




int SpaceCounts(int* iovar_p)
{
    *iovar_p;
    int spaces = 0;
    while (*iovar_p == ' ');
    {
        spaces++;
        *iovar_p = getchar();
    }


    return spaces;
}


//Converts characters to integers; using code from textbook here
int Operand(int* iovar_p)
{
    int operand = 0;


    while (isdigit(*iovar_p))
    {
        operand = operand * 10 + (*iovar_p - '0');
        *iovar_p = getchar();
    }
    return (operand);
}


//Reads in arithmetic operator
char Operator(int* iovar_p)
{
    *iovar_p;
    char ch = (char)*iovar_p;
    switch (ch)
    {
    case '+':
        return ch;
        *iovar_p = getchar();
        break;
    case '-':
        return ch;
        *iovar_p = getchar();


        break;
    case '*':
        return ch;
        *iovar_p = getchar();


        break;
    case '/':
        return ch;
        *iovar_p = getchar();


        break;
    case '%':
        return ch;
        *iovar_p = getchar();


        break;
    default:
        exit(1);
    }






}


//Calculator Function
double answer(int operand1, int operand2, char Arsign)
{
    if (Arsign = '+')
        return (operand1 + operand2);
    else if (Arsign = '-')
        return (operand1 - operand2);
    else if (Arsign = '*')
        return (operand1 * operand2);
    else if (Arsign = '/')
        return ((double)operand1 / operand2);
    else
        return (operand1 % operand2);
}


void PrintSpaces(int spaces)
{
    int i;
    for (i = 0; i < spaces; i++)
        printf(" ");
}