I was trying to compile a program that used a function from math.h and couldn't get it to work, until I found out that I needed to use "gcc -lm test.c", and #include <math.h> in the program wasn't enough. I know from the documentation that -lxxxx searches the library named xxxx when linking, but how do I know what library to name? I wouldn't have guessed that I need -lm when I'm using math.h, and I'm wondering what the chances are that I'll run into this problem again when I need some other library. I'm also using time.h in a program, but I only needed to use an #include statement, with nothing extra on the command line. Phil Carter
