C fprintf() and fscanf()

Writing File : fprintf() function

The fprintf() function is used to write set of characters into file. It sends formatted output to a stream.

Syntax:

int fprintf(FILE *stream, const char *format [, argument, ...])  

Example:

#include <stdio.h>  
main(){  
   FILE *fp;  
   fp = fopen("file.txt", "w");//opening file  
   fprintf(fp, "Hello file by fprintf...\n");//writing data into file  
   fclose(fp);//closing file  
}  

Reading File : fscanf() function
The fscanf() function is used to read set of characters from file. It reads a word from the file and returns EOF at the end of file.

Syntax:

int fscanf(FILE *stream, const char *format [, argument, ...])  

Example:

#include <stdio.h>  
main(){  
   FILE *fp;  
   char buff[255];//creating char array to store data of file  
   fp = fopen("file.txt", "r");  
   while(fscanf(fp, "%s", buff)!=EOF){  
   printf("%s ", buff );  
   }  
   fclose(fp);  
}  
Output:

Hello file by fprintf...

C File Example: Storing employee information
Let's see a file handling example to store employee information as entered by the user from the console. We are going to store id, name, and salary of the employee.

#include <stdio.h>  
void main()  
{  
    FILE *fptr;  
    int id;  
    char name[30];  
    float salary;  
    fptr = fopen("emp.txt", "w+");/*  open for writing */  
    if (fptr == NULL)  
    {  
        printf("File does not exists \n");  
        return;  
    }  
    printf("Enter the id\n");  
    scanf("%d", &id);  
    fprintf(fptr, "Id= %d\n", id);  
    printf("Enter the name \n");  
    scanf("%s", name);  
    fprintf(fptr, "Name= %s\n", name);  
    printf("Enter the salary\n");  
    scanf("%f", &salary);  
    fprintf(fptr, "Salary= %.2f\n", salary);  
    fclose(fptr);  
}  
Output:

Enter the id 
1
Enter the name 
sonoo
Enter the salary
120000 

Now open the file from the current directory. For Windows operating system, go to TC\bin directory, you will see the emp.txt file. It will have the following information.

emp.txt
Id= 1
Name= sonoo
Salary= 120000