fgets
From cppreference.com
| Defined in header <stdio.h>
|
||
| char *fgets( char *str, int count, FILE *stream ); |
(until C99) | |
| char *fgets( char *restrict str, int count, FILE *restrict stream ); |
(since C99) | |
Reads at most count - 1 characters from the given file stream and stores them in str. The produced character string is always null-terminated. Parsing stops if end-of-file occurs or a newline character is found, in which case str will contain that newline character.
Contents |
[edit] Parameters
| str | - | string to read the characters to |
| count | - | the length of str
|
| stream | - | file stream to read the data from |
[edit] Return value
str on success, NULL on failure.
If the failure has been caused by end-of-file condition, additionally sets the eof indicator (see feof()) on stream. If the failure has been caused by some other error, sets the error indicator (see ferror()) on stream.
[edit] Example
fgets with error checking
Run this code
#include <stdio.h> #include <stdlib.h> int main(void) { FILE* tmpf = tmpfile(); fputs("Alan Turing\n", tmpf); fputs("John von Neumann\n", tmpf); fputs("Alonzo Church\n", tmpf); rewind(tmpf); char buf[8]; while (fgets(buf, sizeof buf, tmpf) != NULL) printf("\"%s\"\n", buf); /* Test reason for reaching NULL. */ if (feof(tmpf)) /* if failure caused by end-of-file condition */ puts("End of file reached"); else if (ferror(tmpf)) /* if failure caused by some other error */ { perror("fgets()"); fprintf(stderr,"fgets() failed in file %s at line # %d\n", __FILE__,__LINE__-9); exit(EXIT_FAILURE); } return EXIT_SUCCESS; }
Output:
"Alan Tu" "ring " "John vo" "n Neuma" "nn " "Alonzo " "Church " End of file reached
[edit] References
- C11 standard (ISO/IEC 9899:2011):
- 7.21.7.2 The fgets function (p: 331)
- C99 standard (ISO/IEC 9899:1999):
- 7.19.7.2 The fgets function (p: 296)
- C89/C90 standard (ISO/IEC 9899:1990):
- 4.9.7.2 The fgets function
[edit] See also
| (C11)(C11)(C11) |
reads formatted input from stdin, a file stream or a buffer (function) |
| (until C11)(since C11) |
reads a character string from stdin (function) |
| writes a character string to a file stream (function) | |
| C++ documentation for fgets
| |
