Read mode in c programming

 Read ( r ) mode in C programming

In C programming, the "r" mode is used to open a file for reading. It allows you to read data from the file, but not write to it.

 Example 1:

Write a C program to read a student's name, age, and percentage from the data file "avn.dat" and display all the records on the screen.

 Ans:

#include<stdio.h>

#include<conio.h>

main()

{

char name[20];

int age;

float per;

FILE *fp;

fp=fopen("d:\\avn.dat","r");

while(fscanf(fp,"%s%d%f",name,&age,&per)!=EOF)

{

printf("%s\t%d\t%f\n",name,age,per);

}

fclose(fp);

}

 

Example 2:

A sequential data file"data.txt" has contents name post and salary write a c program to count all the records from that data file.

#include <stdio.h>

#include <stdlib.h>

int main(void)

{

// Open the file for reading

FILE *fp = fopen("data.txt", "r");

 if (fp == NULL)

{

printf("Error opening file!\n");

return 1

}

// Initialize the record count to 0

 int record_count = 0;

// Read the name, post, and salary from the file

char name[100];

char post[100];

float salary;

while (fscanf(fp, "%s %s %f", name, post, &salary) == 3)

{

// Increment the record count

 record_count++;

}

// Print the record count

printf("Number of records: %d\n", record_count);

// Close the file

fclose(fp);

return 0;

}

 

Example 3:

WAP which reads name, department and age from the file named "employee.dat" and display them on the monitor. 

Ans:

#include<stdio.h>

#include<conio.h>

void main()

{

clrscr();

char name[15],dep[20];

int a;

FILE *fp;

fp=fopen("employee.dat","r");

printf("employee name\t Department\t\tAge");

printf("\n----------------------------------");

while(fscanf(fp,"%s%s%d",name,dep,&a)!=EOF)

{

printf("\n%s\t\t%s\t\t%d",name, dep,a);

}

fclose(fp);

getch();

}

Example: 4

A sequential data file emp.txt has contents name post and salary. Write a c program to display all the records whose salary is more then 50000

#include <stdio.h>

main()

  int salary;

{

  char name[100];

  char post[100];

  FILE *fp = fopen("emp.txt", "r");

  while (fscanf(fp, "%s %s %d", name, post, &salary) == 3)

{

 if (salary > 50000)

{

printf("%s %s %d\n", name, post, salary);

}

}

fclose(fp);

}

 

Example 5:

A sequential data file stuent.txt has contains student name and marks of three subjects. Write a c program to display all the passed students only. Assume pass marks is 35 in each subject.

#include <stdio.h>

#include <stdlib.h>

#define PASS_MARK 35

int main()

{

  char name[100];

  int marks1, marks2, marks3;

  while (fscanf(fp, "%s %d %d %d", name, &marks1, &marks2, &marks3) == 4)

{

 if (marks1 >= PASS_MARK && marks2 >= PASS_MARK && marks3 >= PASS_MARK) 

{

 printf("%s\n", name);

 }

 }

 fclose(fp);

 return 0;

}