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fwrite

From cppreference.com
< c‎ | io
Revision as of 17:02, 23 October 2013 by P12 (Talk | contribs)

Defined in header <stdio.h>
size_t fwrite( const void          *buffer, size_t size, size_t count,
               FILE          *stream );
(until C99)
size_t fwrite( const void *restrict buffer, size_t size, size_t count,
               FILE *restrict stream );
(since C99)

Writes count of objects in the given array buffer to the output stream stream. Objects are not interpreted in any way.

Contents

Parameters

buffer - pointer to the first object object in the array to be written
size - size of each object
count - the number of the objects to be written

Return value

The number of objects written successfully.

Example

#include <stdio.h>
 
int main()
{
    // write buffer to file
    FILE *f1;
    char buffer[] = { 'x' , 'y' , 'z' };
    f1 = fopen("file.bin", "wb");
    fwrite(buffer, sizeof(char), sizeof(buffer), f1);
    fclose(f1);
 
    // read the same data and print it to the standard output
    FILE *f2;
    char rbuf[10];
    f2 = fopen("file.bin", "rb");
    const char* res = fgets(rbuf, sizeof(rbuf), f2);
    fclose(f2);
 
    if (res) { // points to rbuf on read success, NULL on failure
        puts(res);
    }
}

Output:

xyz

See also

prints formatted output to stdout, a file stream or a buffer
(function) [edit]
writes a character string to a file stream
(function) [edit]
reads from a file
(function) [edit]