Why is this an infinite (while) loop?

[Think7]

Greetings

I'm currently going though C++ Principals and Practices and starting on loops. I get the concept, how to use them, and what they're for but something is missing.

int main()
{
    char a = 'a';
    while (a < 150) {
        cout << a << endl;
        ++a;
    }
}

This causes an infinite loop and i'm not sure why. a is being incremented by 1 each time, yet the condition of (a < 150) is never met. I'm thinking it might have something to do with conversion / type promotion (or lack thereof) but am not sure. Maybe a isn't being evaluated as an int in the condition?

I realize this is an obnoxiously trivial question but can't seem to find an answer elsewhere. I apologize in advance if it's a repost or if i missed something.

Thank you in advance!

[booradley60]

Range of char is -128 to 127. '++a' wraps from 127 to -128. Try declaring a as an unsigned char instead of char and see what happens.

[vlad from moscow]

Whether this loop will be infinite depends on options of the compiler you are using. Type char can behave either as signed char or as unsigned char.

[Think7]

That did it! Thank you so much!!! :)