fgetpos - Linux
Overview
fgetpos retrieves the current file position of the specified stream in a posix-compliant way. It is commonly used in conjunction with fsetpos to modify or restore the file pointer.
Syntax
int fgetpos(FILE *stream, fpos_t *pos);
Options/Flags
None.
Examples
Example 1: Retrieve the current file position
#include <stdio.h>
#include <stdlib.h>
int main() {
FILE *fp = fopen("myfile.txt", "r");
if (fp == NULL) {
perror("fopen");
exit(EXIT_FAILURE);
}
fpos_t pos;
if (fgetpos(fp, &pos) != 0) {
perror("fgetpos");
fclose(fp);
exit(EXIT_FAILURE);
}
printf("Current file position: %d\n", pos);
fclose(fp);
return 0;
}
Example 2: Restore the file position using fsetpos
// Assuming fp is an open file stream
fpos_t saved_pos;
if (fgetpos(fp, &saved_pos) != 0) {
// Handle error
}
// ... Some operations that modify the file pointer
if (fsetpos(fp, &saved_pos) != 0) {
// Handle error
}
Common Issues
- Ensure that
stream
is a valid file stream that has been opened for reading or writing. Attempting to get the position of a closed stream will result in an error. - The type of
pos
must befpos_t
, which is a platform-dependent data type. To ensure portability, it is recommended to usefpos_t
instead oflong
orint
.
Integration
fgetpos can be used in conjunction with other file manipulation functions, such as:
fseek
andftell
to manually control the file pointer.fread
andfwrite
to read and write data from and to the file at specific positions.rewind
to reset the file pointer to the beginning of the stream.
Related Commands
fsetpos
: Sets the file position of a stream.fseek
: Sets the file position of a stream based on an offset.ftell
: Retrieves the current file position within a stream.