I am working in Eclipse 3.7.2 on Ubuntu 12.04 with C++. I have read about a few instances where libraries were not being recognized and the majority said to update the Paths and Symbols but that hasn't fixed my issue. I have 2 projects open in my workspace, one of which is already a completed project that has implemented functions and libraries with no errors from Eclipse. However, when I try to implement some of the same functions or include the same libraries in the 2nd project Eclipse can't resolve them. For example,

#include <string>
#include <stdio.h>
strstr(p, "<Project>"); 

The include statement will be accepted and stdio.h will be found but the strstr function is not resolved even though it works fine in the other project. Any ideas as to why this might be happening? Thanks.