Why Does C Forbid Comparing Pointers and Integers?

Compiler Error: ISO C 's Prohibition of Pointer-Integer Comparisons

While experimenting with a simple function from Bjarne Stroustrup's C textbook, developers frequently encounter the compile error: "ISO C forbids comparison between pointer and integer." This error stems from the comparison between a pointer and an integer.

One instance of this issue arises when comparing a character input to the string "y". In the provided code:

<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 because the code defines answer as a character (char), while "y" is a string literal. To resolve this, you have two options:

1. Convert the string literal to a character: Use answer == 'y' to compare the character input to the character 'y'.
2. Use a string instead of a character: Declare answer as a string (string answer;) and then compare it to the string "y".

Both solutions address the compiler's restriction by ensuring that you are comparing a pointer to an integer with a pointer to another integer or a pointer to a string.

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