fopen
FILE * fopen (const char * filename, const char * mode);
fclose
int fclose (FILE * stream);
fread
size_t fread (void * ptr, size_t size, size_t count, FILE * stream);
Read block of data from stream reads an array to count elements, each one with a size of size bytes, from the stream an D stores them in the blocks of memory specified by PTR.
The position indicator of the stream is advanced by the total amount of bytes read.
The total amount of bytes read if successful is (Size*count).
fwrite
size_t fwrite (const void * ptr, size_t size, size_t count, FILE * stream);
Write block of data to stream writes a-array of count elements, each one with a size of size bytes, from the block of M Emory pointed by PTR to the current position in the stream.
The position indicator of the "stream is advanced by" total number of bytes written.
Internally, the function interprets the block pointed by PTR as if it is an array of (Size*count) elements of type uns Igned Char, and writes them sequentially to stream as if FPUTC is called for each byte.
fseek
int fseek (FILE * stream, long int offset, int origin);
Reposition Stream Position Indicator Sets The position indicator with the stream to a new associated.
For streams open in binary mode, the new position was defined by adding offset to a reference position of specified by origin .
For streams open in text mode, offset shall either is zero or a value returned by a previous call to Ftell, and origin shall necessarily be seek_set.
If The function is called with other values for this arguments, support depends on the particular system and library Impl Ementation (non-portable).
The End-of-file internal indicator of the The stream is cleared after a successful call to this function, and all effects fr Om previous calls to ungetc on the this stream are dropped.
On streams open for Update (read+write), a call to Fseek allows to switch between reading and writing.
ParametersStream pointer to a FILE object that identifies the stream. Offset Binary files:number of bytes to offset from origin.
Text Files:either Zero, or a value returned by Ftell. Origin Position used as reference for the offset. It is specified by one of the "following constants defined in <cstdio>exclusively to" used as arguments for this F Unction:
| Constant |
Reference Position |
| Seek_set |
Beginning of File |
| Seek_cur |
Current position of the file pointer |
| Seek_end |
End of File * |
* Library implementations are allowed to don't meaningfully support seek_end (therefore, code using it has no real standard Portability).
Ftell
Long int Ftell (FILE * stream);
Get-position in stream Returns the current value of the position indicator of the stream.
For binary streams, this is the number of bytes from the beginning of the file.
For text streams, the numerical value may is meaningful but can still is used to restore the position to the same tion later using fseek (if there are characters put back using ungetc still pending of being read, the behavior is undef ined).
reference materials
http://www.cplusplus.com/
