Question

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main()
{
    FILE *fp;
    char ch;
    char buffer[80] ;
    fp = fopen("c:\\Rasmi Personal\\hello.txt", "w");

    if(fp == NULL)
    {
        printf("File not found");
        exit(1);
    }
    else
    {
        while(1)
        {
            gets(buffer);
            fwrite(buffer, strlen(buffer), 2, fp); /* I made, size_t nitems = 2 (third element/argument)*/
            fwrite("\n", 1, 1, fp);
        }

    }

    fclose(fp);

    return 0;
}

Input:

Rasmi Ranjan Nayak

Output:

Rasmi Ranjan Nayak      0@ ÿ" 8ÿ" 

Why this garbage is coming.

According to fwrite() function. if the size_t nitems is more than 1 then the entered text will be written more than once.
But here why I am getting garbage?

Answer 1

The signature of fwrite function is

size_t fwrite ( const void * ptr, size_t size, size_t count, FILE * stream );

ptr
  Pointer to the array of elements to be written.
size
  Size in bytes of each element to be written.
count
  Number of elements, each one with a size of size bytes.
stream
  Pointer to a FILE object that specifies an output stream.

In this case, if you try to write count * size who is bigger (in bytes) than the original string you have this garbage. If you clean the buffer

memset(buffer,0,80*sizeof(char));
gets(buffer);

probably will see a different result

$ ./a.out
asdadsadasdsad

$ cat -v hello.txt 
asdadsadasdsad^@^@^@^@^@^@^@^@^@^@^@^@^@^@

but the text is always writen once. the difference is how many bytes will be writen