function
<cstdio>

fwrite

size_t fwrite ( const void * ptr, size_t size, size_t count, FILE * stream );
Write block of data to stream
Writes an array of count elements, each one with a size of size bytes, from the block of memory pointed by ptr to the current position in the stream.

The position indicator of the stream is advanced by the total number of bytes written.

Internally, the function interprets the block pointed by ptr as if it was an array of (size*count) elements of type unsigned char, and writes them sequentially to stream as if fputc was called for each byte.

Parameters

ptr
Pointer to the array of elements to be written, converted to a const void*.
size
Size in bytes of each element to be written.
size_t is an unsigned integral type.
count
Number of elements, each one with a size of size bytes.
size_t is an unsigned integral type.
stream
Pointer to a FILE object that specifies an output stream.

Return Value

The total number of elements successfully written is returned.
If this number differs from the count parameter, a writing error prevented the function from completing. In this case, the error indicator (ferror) will be set for the stream.
If either size or count is zero, the function returns zero and the error indicator remains unchanged.
size_t is an unsigned integral type.

Example

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/* fwrite example : write buffer */
#include <stdio.h>

int main ()
{
  FILE * pFile;
  char buffer[] = { 'x' , 'y' , 'z' };
  pFile = fopen ("myfile.bin", "wb");
  fwrite (buffer , sizeof(char), sizeof(buffer), pFile);
  fclose (pFile);
  return 0;
}


A file called myfile.bin is created and the content of the buffer is stored into it. For simplicity, the buffer contains char elements but it can contain any other type.
sizeof(buffer) is the length of the array in bytes (in this case it is three, because the array has three elements of one byte each).

See also

fread
Read block of data from stream (function )
fprintf
Write formatted data to stream (function )
putc
Write character to stream (function )
fputc
Write character to stream (function )

C++