What is header file #include ?

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*The C programming language provides many standard library functions for file input and output. These functions make up the bulk of the C standard library header <stdio.h>.

• The first thing you will notice is the first line of the file, the #include "stdio.h" line. This is very much like the #define the preprocessor , except that instead of a simple substitution, an entire file is read in at this point.
• The system will find the file named "stdio.h" and read its entire contents in, replacing this statement.
• Obviously then, the file named "stdio.h" must contain valid C source statements that can be compiled as part of a program.
• This particular file is composed of several standard #defines to define some of the standard I/O operations.
• The file is called a header file and you will find several different header files on the source disks that came with your C compiler.
• Each of the header files has a specific purpose and any or all of them can be included in any program.
• Your C compiler uses the double quote marks to indicate that the search for the "include" file will begin in the current directory, and if it not found there, the search will continue in the "include" directory as set up in the environment.
• It also uses the "less than" and "greater than" signs to indicate that the file search should begin in the directory specified in the environment.
• Most of the programs in this tutorial have the double quotes in the "include" statements. The next program uses the "<" and ">" to illustrate the usage.
• Note that this will result is a slightly faster (but probably unnoticeable) compilation because the system will not bother to search the current directory.

C – stdio.h library functions

  ********All C inbuilt functions which are declared in stdio.h header file are given below.********

List of inbuilt C functions in stdio.h file:

1. printf() This function is used to print the character, string, float, integer, octal and hexadecimal values onto the output screen
2. scanf() This function is used to read a character, string, numeric data from keyboard.
3. getc() It reads character from file
4. gets() It reads line from keyboard
5. getchar() It reads character from keyboard
6. puts() It writes line to o/p screen
7. putchar() It writes a character to screen
8. clearerr() This function clears the error indicators
9. f open() All file handling functions are defined in stdio.h header file
10. f close() closes an opened file
11. getw() reads an integer from file
12. putw() writes an integer to file
13. f getc() reads a character from file
14. putc() writes a character to file
15. f putc() writes a character to file
16. f gets() reads string from a file, one line at a time
17. f puts() writes string to a file
18. f eof() finds end of file
19. f getchar reads a character from keyboard
20. f getc() reads a character from file
21. f printf() writes formatted data to a file
22. f scanf() reads formatted data from a file
23. f getchar reads a character from keyboard
24. f putchar writes a character from keyboard
25. f seek() moves file pointer position to given location
26. SEEK_SET moves file pointer position to the beginning of the file
27. SEEK_CUR moves file pointer position to given location
28. SEEK_END moves file pointer position to the end of file.
29. f tell() gives current position of file pointer
30. rewind() moves file pointer position to the beginning of the file
31. putc() writes a character to file
32. sprint() writes formatted output to string
33. sscanf() Reads formatted input from a string
34. remove() deletes a file
35. fflush() flushes a file