fgets
| Defined in header
<stdio.h>
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||
| char *fgets( char *str, int count, FILE *stream );
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(until C99) | |
| char *fgets( char *restrict str, int count, FILE *restrict stream );
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(since C99) | |
Reads at most count - 1 characters from the given file stream and stores them in the character array pointed to by str. Parsing stops if end-of-file occurs or a newline character is found, in which case str will contain that newline character. If no errors occur, writes a null character at the position immediately after the last character written to str.
The behavior is undefined if count is less than 1.
Contents |
[edit] Parameters
| str | - | pointer to an element of a char array |
| count | - | maximum number of characters to write (typically the length of str)
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| stream | - | file stream to read the data from |
[edit] Return value
str on success, null pointer on failure.
If the failure has been caused by end-of-file condition, additionally sets the eof indicator (see feof()) on stream. The contents of the array pointed to by str are not altered in this case.
If the failure has been caused by some other error, sets the error indicator (see ferror()) on stream. The contents of the array pointed to by str are indeterminate (it may not even be null-terminated).
[edit] Notes
POSIX additionally requires that fgets sets errno if it encounters an failure other than the end-of-file condition.
Although the standard specification is ambiguous in the case where count==1, common implementations read no characters, store zero in str[0], and report success (return str)
[edit] Example
#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); if (feof(tmpf)) puts("End of file reached"); }
Output:
"Alan Tu" "ring " "John vo" "n Neuma" "nn " "Alonzo " "Church " End of file reached
[edit] References
- C11 standard (ISO/IEC 9899:2011):
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- 7.21.7.2 The fgets function (p: 331)
- C99 standard (ISO/IEC 9899:1999):
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- 7.19.7.2 The fgets function (p: 296)
- C89/C90 standard (ISO/IEC 9899:1990):
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- 4.9.7.2 The fgets function
[edit] See also
| (C11)(C11)(C11)
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reads formatted input from stdin, a file stream or a buffer (function) |
| (until C11)(since C11)
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reads a character string from stdin (function) |
| writes a character string to a file stream (function) |
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| (dynamic memory TR)
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read from a stream into a automatically resized buffer until delimiter/end of line (function) |
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C++ documentation for fgets
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