C Standard Library:

C would have been a tough programming language in absence of the standard library. The standard library in C includes header files and standard functions in these files. Header files are collection of macros, types, functions and constants. Any program that needs those functions has to include these header files. For example, the standard library functions, included in “stdlib.h” header file, are used for number conversions, storage allocation and other functions on the same line. These functions are called utility functions. C does not have any built-in input/output statements as part of its syntax. All I/O operations are carried out through function calls such as printf and scanf. There are many functions that have become standard for I/O operations in C, collectively known as standard I/O library “stdio.h”. Because of this standard inputoutput header file, standard I/O functions can be used on many machines without any change.