What is fwrite?

The fwrite() function writes binary and text data from an array to a given data stream. It is available in both C and C++.

Parameters

std::size_t fwrite( const void* buffer, std::size_t size, std::size_t count, std::FILE* stream );

  • buffer: points to the first object in the array to be written
  • size: the item size in bytes
  • count: the number of the objects to be written
  • stream: points to a FILE object that specifies an output stream

Return value

The function returns the total number of elements that were successfully written. If this number is less than the count it signifies that an error has prevented all the characters from being written.

Code example

The following code shows how to write to a file using fwrite():

main.cpp
file.txt
#include <cstdio>
#include <iostream>
using namespace std;
int main()
{
    int retVal;
    FILE *fp;
    char buffer[] = "Example text";
    fp = fopen("file.txt","w");
    int returns = fwrite(buffer,sizeof(buffer),1,fp);
    
    cout << "fwrite returned " << returns;
    return 0;
}

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