hi

I am using sleep function in a C++ program. when I compile this program using g++.I am getting followong error:

Code:
g++ samspec.cpp samspecCount.cpp -o samspec
samspecCount.cpp: In function `void* Counter_fun(void*)':
samspecCount.cpp:26: `sleep' undeclared (first use this function)
samspecCount.cpp:26: (Each undeclared identifier is reported only once for each function it appears in.)
...