what does the signed/unsigned comparison warning mean?

Question

auto.cpp: In function ‘int autooo(unsigned int)’:
auto.cpp:33:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]

Answer 1

The compiler warns that the code contains comparison of unsigned int with a signed int in the line

while (numberFound < b);

This has nothing to do with makefiles or make.

You can fix that by changing

int b=50;

to

unsigned b = 50;

or by changing

unsigned numberFound = 0;

to

int numberFound = 0;

The problems you might run into when comparing signed int and unsigned int are explained in this answer to another SO question