fgetpos
From cppreference.com
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Defined in header
<stdio.h>
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| (until C99) | ||
| (since C99) | ||
Obtains the file position indicator and the current parse state (if any) for the file stream
stream
and stores them in the object pointed to by
pos
. The value stored is only meaningful as the input to
fsetpos
.
Parameters
| stream | - | file stream to examine |
| pos | - | pointer to a fpos_t object to store the file position indicator to |
Return value
0 upon success, nonzero value otherwise.
Example
Run this code
#include <stdio.h> #include <stdlib.h> #include <assert.h> int main(void) { // prepare a file holding 4 values of type double enum {SIZE = 4}; FILE* fp = fopen("test.bin", "wb"); assert(fp); int rc = fwrite((double[SIZE]){1.1, 2.2, 3.3, 4.4}, sizeof(double), SIZE, fp); assert(rc == SIZE); fclose(fp); // demo using fsetpos to return to the beginning of a file fp = fopen("test.bin", "rb"); fpos_t pos; fgetpos(fp, &pos); // store start of file in pos double d; rc = fread(&d, sizeof d, 1, fp); // read the first double assert(rc == 1); printf("First value in the file: %.1f\n", d); fsetpos(fp,&pos); // move file position back to the start of the file rc = fread(&d, sizeof d, 1, fp); // read the first double again assert(rc == 1); printf("First value in the file again: %.1f\n", d); fclose(fp); // demo error handling rc = fsetpos(stdin, &pos); if(rc) perror("could not fsetpos stdin"); }
Output:
First value in the file: 1.1 First value in the file again: 1.1 could not fsetpos stdin: Illegal seek
References
- C11 standard (ISO/IEC 9899:2011):
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- 7.21.9.1 The fgetpos function (p: 336)
- C99 standard (ISO/IEC 9899:1999):
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- 7.19.9.1 The fgetpos function (p: 302)
- C89/C90 standard (ISO/IEC 9899:1990):
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- 4.9.9.1 The fgetpos function
See also
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returns the current file position indicator
(function) |
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moves the file position indicator to a specific location in a file
(function) |
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moves the file position indicator to a specific location in a file
(function) |
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C++ documentation
for
fgetpos
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