Library Functions
C library functions are commonly needed functions that have been predefined.
To use a library function, include the appropriate header file and link in the library during compilation. Example: #include <math.h> in “p1.c” and then % gcc p1.c -lm
Not including these files can lead to potential problems: Unless we add #include <math.h> the output to this program: main() { printf(“2 cubed is %f\n”,pow(2,3)); } is 0.000