Question

What is a library function?  

Answer 1

Library functions are predefined inbuilt functions which are grouped together and kept in a common library file. To use these functions in our program we have to import/include the specifc library in our code. Each library function performs specific operation. Most probabaly these Library functions are coded by the people who designed and created compilers or interpreters.

for eg in C : stdio.h is the header file in which Input/Output functions ( printf() ,scanf() ) are declared. We can even rewrite the library functions as our need. But it is not preferrable since most of these functions are universally accepted and followed for many years.

Other eg: math.h for all math related functions like pow() , string.h for all string related functions and so on ....