C2106 Error in Simple Math Program

Question

#include <tchar.h>
#include <stdio.h>
#include <iostream>
using namespace std;

int main()
{
    int a = (1024^3)-(639^3)-(385^3);
    short max = 0;
    cout<< " Prints 0 if no answer." << endl;

    for(int iii = 100; iii < 1000; iii++)
    {
        if(a % iii = 0)
        {
            max = iii;
        }
    }
    cout<< " " << max;

    cin.clear(); cin.ignore(); cin.get();
    return 0;
}

Just trying to write a simple program so I don't have to calculate and the compiler returns a C2106 error for line 14.

I doubt the compiler only says "C2106 error for line 14". Please provide the **complete** error message, and also add a comment in your code to indicate where is line 14 so we don't have to count. — syam, Apr 25 '13 at 11:54
did you intend to use caret (^) as a exponentiation operator? i don't think it works this way in c++ — Vladimir, Apr 25 '13 at 11:56

score 3 · Answer 1 · answered Apr 25 '13 at 11:56

if (a % iii = 0)

This is an invalid assignment. If you meant to compare, use the comparison operator ==.

if (a % iii == 0)

Moreover, exponentiation is not done with ^ in C++. That is actually the bitwise xor operator. To do exponentation, use std::pow from the <cmath> header.

#include <cmath>

int main()
{
    int a = std::pow(1024, 3) - std::pow(639, 3) - std::pow(385, 3);
}

score 1 · Answer 2 · answered Apr 25 '13 at 11:54

1

Should be == for comparision

       if((a % iii) == 0)

answered Apr 25 '13 at 11:54

suspectus

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score 1 · Answer 3 · edited May 23 '17 at 10:24

You are using the assignment operator = instead of the equality operator ==:

if(a % iii = 0)

This should be:

if( a % iii == 0)

The result of a % iii is a temporary and and in the original code you are trying to assign 0 to that temporary. Besides that error it looks like you are trying to raise some numbers by a power here:

int a = (1024^3)-(639^3)-(385^3);

the ^ operator is actually bitwise xor what you need is pow from the cmath header:

int a = std::pow(1024,3)-std::pow(639,3)-std::pow(385,3);

I would also avoid using namespace std.

C2106 Error in Simple Math Program

3 Answers3