In this tutorial we will learn to read and write multiple data in files in C programming language.
In the previous tutorials we have learned how to read and write characters in files in C and how to read and write integers in files in C. In both the cases we worked with single character and integer at a time. Now we will learn to handle multiple data using fscanf() and fprintf() functions.
We know how to use scanf() function to take input and printf() function to print the output.
In a similar way, we use the fscanf() function to read data from the file and fprintf() function to write data in the file.
Syntax of fscanf function:
fscanf(fptr, "control string", list_of_var); Where, fptr is a file pointer. The control string contains the input specification like %d for integer or %c for character. list_of_var is the list of variables.
Syntax of fprintf function:
fprintf(fptr, "control string", list_of_var); We will create a student file for this program.
We will use the fprintf() function to write the data in the file and then using the fscanf() function to read the data from the file.
#include int main(void) < // creating a FILE variable FILE *fptr; // integer variable int id, score; int i, s; // character variable char name[255]; char n[255]; // open the file in write mode fptr = fopen("student", "w"); if (fptr != NULL) < printf("File created successfully!\n"); >else < printf("Failed to create the file.\n"); // exit status for OS that an error occured return -1; >// get student detail printf("Enter student name: "); gets(name); printf("Enter student ID: "); scanf("%d", &id); printf("Enter student score: "); scanf("%d", &score); // write data in file fprintf(fptr, "%d %d %s", id, score, name); // close connection fclose(fptr); // open file for reading fptr = fopen("student", "r"); // display detail printf("\nStudent Details:\n"); fscanf(fptr, "%d %d %[^\n]s", &i, &s, n); printf("ID: %d\n", i); printf("Name: %s\n", n); printf("Score: %d\n", s); printf("\nEnd of file.\n"); // close connection fclose(fptr); return 0; > File created successfully! Enter student name: Yusuf Shakeel Enter student ID: 100 Enter student score: 9 Student Details: ID: 100 Name: Yusuf Shakeel Score: 9 End of file. Content of the student file.
We can also use the fscanf and fprintf function to read data from the standard input stdin like keyboard and write data to the standard output stdout like monitor.
In the following example we are taking id and score from user and printing it.
#include int main(void) < // variables int id, score; // take user input printf("Enter ID: "); fscanf(stdin, "%d", &id); printf("Enter Score: "); fscanf(stdin, "%d", &score); // print output printf("\nDetail:\n"); fprintf(stdout, "ID: %d\n", id); fprintf(stdout, "Score: %d\n", score); return 0; >Enter ID: 1 Enter Score: 20 Detail: ID: 1 Score: 20 