The **`fprintf` function** allows the programmer to redirect the standard output to a file instead of the console. Simply put, it lets the programmer write a string into a file.



# Difference between ```printf``` and ```fprintf```



As shown in the figure above, ```fprintf``` works exactly like ```printf```, but for files. It prints the content of the character array into the file specified by the programmer.

# Syntax
```C
int fprintf(FILE *pointerToFile, const char *stringToPrint, ...);
```
In the above snippet of code, `pointerToFile` is the pointer of type `FILE` returned by the `fopen` function, and `stringToPrint` is the character array that is to be printed in the file. 


# Return Value
If the function executes successfully, it will return the number of characters written into the file. 

In case of failure, a negative number is returned.

## Example 1
The following piece of code prints a simple *_Hello, World!_* statement in the file *_output.txt_*:


#include<stdio.h>
int main() {
  
  // sample string to write in the file
  char sampleString[] = "Hello, World!";
  char str[1000];

  //opening the file for writing
  FILE *filePointer = fopen("output.txt", "w+");

  // checking if the file opened successfuly
  if(filePointer != NULL){
    
    // writing in the file
    int response = fprintf(filePointer, sampleString);

    // checking if fprintf executed successfully
    if(response < 0){
      printf("Unable to write in the specified file.");
    }

  }

  // closing the file
  fclose(filePointer);

  // reading file to see if the write was successful
  filePointer = fopen("output.txt", "r");

  while (fgets(str, 1000, filePointer) != NULL){
    printf("Text file: %s", str);
  }

  fclose(filePointer);  


  return 0;
}

## Example 2
The following piece of code prints numbers 1 to 10 (in each line) in the specified file:

#include<stdio.h>
int main() {
  
  //opening the file for writing
  FILE *filePointer = fopen("output.txt", "w+");
  char str[1000];
  
  // checking if the file opened successfuly
  if(filePointer != NULL){
    
    // loop to print the numbers 1 to 10
    for(int i = 1; i <= 10; i++){
      fprintf(filePointer, "%d\n", i);
    }
  }

  // closing the file
  fclose(filePointer);


   // reading file to see if the write was successful
  filePointer = fopen("output.txt", "r");

  while (fgets(str, 1000, filePointer) != NULL){
    printf("Text file: %s", str);
  }

  fclose(filePointer);  

  return 0;
}

What is fprintf in C?

fprintf redirects standard output to a file, working like printf but for files, and returns character count or negative on failure.

What is fprintf in C?

Difference between printf and fprintf

Syntax

Return Value

Example 1

Example 2

Difference between `printf` and `fprintf`