fopen
From cppreference.com
| Defined in header <stdio.h>
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| FILE *fopen( const char *filename, const char *mode ); |
(until C99) | |
| FILE *fopen( const char *restrict filename, const char *restrict mode ); |
(since C99) | |
Opens a file indicated by filename and returns a file stream associated with that file. mode is used to determine the file access mode.
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[edit] Parameters
| filename | - | file name to associate the file stream to | |||||||||||||||||||||||||||||||||||||||||||||
| mode | - | null-terminated character string determining file access mode
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[edit] Return value
If successful, returns a pointer to the object that controls the opened file stream, with both eof and error bits cleared. The stream is fully buffered unless filename refers to an interactive device.
On error, returns a null pointer. POSIX requires that errno is set in this case.
[edit] Notes
The format of filename is implementation-defined, and does not necessarily refer to a file (e.g. it may be the console or another device accessible though filesystem API). On platforms that support them, filename may include absolute or relative filesystem path.
[edit] Example
fopen with error checking. Code opens a file for writing data.
Run this code
#include <stdio.h> #include <stdlib.h> int main(void) { FILE *fp = fopen("data.txt","w"); if (fp == NULL) { perror("fopen()"); fprintf(stderr,"fopen() failed in file %s at line # %d\n", __FILE__,__LINE__-4); return EXIT_FAILURE; } /* Normal processing continues here. */ fclose(fp); return EXIT_SUCCESS; }
[edit] See also
| closes a file (function) | |
| synchronizes an output stream with the actual file (function) | |
| open an existing stream with a different name (function) | |
| C++ documentation for fopen
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