- Library functions in C language are inbuilt functions which are grouped together and placed in a common place called library.
- Each library function in C performs specific operation.
- We can make use of these library functions to get the pre-defined output instead of writing our own code to get those outputs.
- These library functions are created by the persons who designed and created C compilers.
- All C standard library functions are declared in many header files which are saved as file_name.h.
- Actually, function declaration, definition for macros are given in all header files.
- We are including these header files in our C program using “#include<file_name.h>” command to make use of the functions those are declared in the header files.
- When we include header files in our C program using “#include<filename.h>” command, all C code of the header files are included in C program. Then, this C program is compiled by compiler and executed.
Please check the below links for actual C source code for the respective C header files.
- If you want to check source code for all header files, you can check inside “include” directory after C compiler is installed in your machine.
- For example, if you install DevC++ compiler in C directory in your machine, “C:\Dev-Cpp\include” is the path where all header files will be available.
List of most used header files in C programming language:
- Check the below table to know all the C library functions and header files in which they are declared.
- Click on the each header file name below to know the list of inbuilt functions declared inside them.
|stdio.h||This is standard input/output header file in which Input/Output
functions are declared
|conio.h||This is console input/output header file|
|string.h||All string related functions are defined in this header file|
|stdlib.h||This header file contains general functions used in C programs|
|math.h||All maths related functions are defined in this header file|
|time.h||This header file contains time and clock related functions|
|ctype.h||All character handling functions are defined in this header file|
|stdarg.h||Variable argument functions are declared in this header file|
|signal.h||Signal handling functions are declared in this file|
|setjmp.h||This file contains all jump functions|
|locale.h||This file contains locale functions|
|errno.h||Error handling functions are given in this file|
|assert.h||This contains diagnostics functions|