fwrite()
Write elements to a file
Synopsis:
#include <stdio.h> size_t fwrite( const void* buf, size_t size, size_t num, FILE* fp );
Arguments:
- buf
- A pointer to a buffer that contains the elements that you want to write.
- size
- The size of each element to write.
- num
- The number of elements to write.
- fp
- The stream to which to write the elements.
Library:
libc
Use the -l c option to qcc to link against this library. This library is usually included automatically.
Description:
The fwrite() function writes num elements of size bytes each to the stream specified by fp.
Returns:
The number of complete elements successfully written; if an error occurs, this is less than num.
Errors:
If an error occurs, errno is set to indicate the type of error.
Examples:
#include <stdio.h> #include <stdlib.h> struct student_data { int student_id; unsigned char marks[10]; }; int main( void ) { FILE *fp; struct student_data std; int i; fp = fopen( "file", "w" ); if( fp != NULL ) { std.student_id = 1001; for( i = 0; i < 10; i++ ) { std.marks[i] = (unsigned char)(85 + i); } /* write student record with marks */ i = fwrite( &std, sizeof( struct student_data ), 1, fp ); printf( "Successfully wrote %d records\n", i ); fclose( fp ); if( i == 1 ) { return EXIT_SUCCESS; } } return EXIT_FAILURE; }
Classification:
Safety: | |
---|---|
Cancellation point | Yes |
Interrupt handler | No |
Signal handler | No |
Thread | Yes |