stdio.h summary

Functions:

clearerr	Reset error indicators.
fclose	Close a stream.
feof	Check if End Of File has been reached.
ferror	Check for errors.
fflush	Flush a stream.
fgetc	Get next character from a stream.
fgetpos	Get position in a stream.
fgets	Get string from a stream.
fopen	Open a file.
fprintf	Print formatted data to a stream.
fputc	Write character to a stream.
fputchar	Write character to stdout.
fputs	Write string to a stream.
fread	Read block of data from a stream.
freopen	Reopen a file using a different file mode.
fscanf	Read formatted data from a stream.
fseek	Reposition stream's position indicator.
fsetpos	Reposition file pointer to a saved location.
ftell	Return the current position of the file pointer.
fwrite	Write block of data to a stream.
getc	Get the next character.
getchar	Get the next character from stdin.
gets	Get a string from stdin.
getw	Get the next int value from a stream.
perror	Print error message.
printf	Print formatted data to stdout.
putc	Write character to a stream.
putchar	Write character to stdout.
puts	Write a string to stdout.
putw	Write an integer to a stream.
remove	Delete a file.
rename	Rename a file or directory.
rewind	Reposition file pointer to the beginning of a stream.
scanf	Read formatted data from stdin.
setbuf	Change stream buffering.
setvbuf	Change stream buffering.
sprintf	Format data to a string.
sscanf	Read formatted data from a string.
tmpfile	Open a temporary file.
tmpnam	Generate a unique temporary filename.
ungetc	Push a character back into stream.

stdio.h summary:

Streams.
  Streams are an abstraction used in C and C++ for input and output operations through I/O devices based on characters, like files, keyboard, printer, screen and I/O ports.
  A stdio.h stream is represented by a pointer to a FILE structure that contains internal info about properties and indicators of a file. Normally data contained in these structures are not referred directly. When using stdio.h functions, pointer to FILE structures are only used to be passed as parameters to I/O functions.

Properties.

  A stream has some properties that defines which functions can be used with it or how the functions will treat the stream. Most of them are defined in the mode parameter when fopen function is called.

Access

Specifies if the operations performed with the stream will have read and/or write access to the file.

Text / Binary

Text files are those where lines are delimited by the special character EOL (End Of Line), and some translations occur when this special character is read or written for that these file can be directly outputed to a console. The End of a text file is defined by the first occurrence of the EOF character.

A binary file is a file where each byte is read or written as a character, no translations occur, and the End of a binary file matches with the physical End of the File.

Buffer

A buffer is a block of memory where data is accumulated before being physically read or written to the file. Buffered stream causes I/O operations with the stream to be faster because normally buffers are faster than physical devices like disks or ports. A stream can be unbuffered so the data is directly read or written to the device. The use of stream buffers can be specified using functions setbuf and setvbuf.

Indicators.

  A stream has some indicators that specify the current state of it. These are internally modified and affect the behavior of Input/Output functions:

Error Indicator

This indicator is set when an error has occurred in an operation related with the stream. This indicator can be checked using ferror, and can be reset by a call to clearerr or by any repositioning functions (rewind, fseek and fsetpos).

End-Of-File Indicator

When this indicator is set, the last reading or writing operation permormed has reached the End of the file associated with the stream. This can be checked with the feof function, and can be reset by calling to clearerr or by any repositioning functions (rewind, fseek and fsetpos).

Position Indicator (File pointer)

This indicator is an internal pointer that points to the next character within the stream that has to be read or written by the next I/O operation. This value can be obtained by the ftell and fgetpos functions, and can be changed calling to rewind, fseek and fsetpos functions

Standard Streams

  When a program that includes stdio.h begin its execution, three predefined streams are opened:

stdin

This is the standard input stream. By default stdin corresponds to the keyboard, but this can be redirected by the operating system.

stdout

This is the standard output stream. By default stdout is directed to the screen, but the operating system can redirect it to a file or any other output device.

stderr

The standard error stream. This is an output stream specifically intendend to receive error messages. By default is directed to the standard output (like stdout), but it can be redirected to a log file or any other output device.