Why am I Getting a \"Compile Error: ISO C Forbids Comparison Between Pointer and Integer\"?

Compile Error: "ISO C Forbids Comparison Between Pointer and Integer"

When trying to compile a function in C , you may encounter a "compile error: ISO C forbids comparison between pointer and integer." This error results from an attempt to compare a pointer value with an integer.

The Issue

In the provided code snippet:

<code class="cpp">#include <iostream>
#include <string>
using namespace std;

bool accept() {
    cout << "Do you want to proceed (y or n)?\n";
    char answer;
    cin >> answer;
    if (answer == "y") return true;
    return false;
}</code>

The error occurs on the line:

<code class="cpp">if (answer == "y") return true;</code>

Here, the variable answer is declared as a char, while the string literal "y" is a string. Comparing a char pointer to a string literal is forbidden in ISO C , as it can lead to subtle errors.

Solutions

There are two ways to fix this issue:

1. Convert answer to a string:

<code class="cpp">string answer;</code>

This approach is preferred because it aligns with modern C best practices.

2. Use single quotes for the string literal:

<code class="cpp">if (answer == 'y') ...</code>

Single quotes denote a char constant, which is compatible with the char variable answer.

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