C++ File Handling

C++ File Handling is used to store data on a file. A file is a collection of related data stored in the disk. Programs can be designed to perform the read and write operations on these files.

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#include<iostream.h>
#include<conio.h>
#include<fstream.h>
void main()
{
    char a[20];
    clrscr();
    cout<<"Enter name";
    cin>>a;
    ofstream out("file.txt");
    out<<a;
    out.close();
    getch();
}

#include<iostream.h>
#include<conio.h>
#include<fstream.h>

void main()
{
    char a[20];
    clrscr();
    ifstream in("file.txt");
    in>>a;
    cout<<a;
    in.close();
    getch();
}

Example 3: Write the text in a file then Read its contents. 1

#include<iostream.h>
#include<conio.h>
#include<fstream.h>

void main()
{
    char a[20], b[20];
    clrscr();
    cout<<"Enter name";
    cin>>a;
    ofstream out("file.txt");
    out<<a;
    out.close();
    ifstream out2("file.txt");
    out2>>b;
    cout<<b;
    out2.close();
    getch();
}

Example 4: Input file name and display its contents if exists using getline function. 1

#include<iostream.h>
#include<conio.h>
#include<fstream.h>

void main()
{
    char a[20], b[20];
    clrscr();
    cout<<"Enter filename";
    cin>>a;
    cout<<"File Contents are\n";
    ifstream f;
    f.open(a);
    while(f)
    {
        f.getline(b,80);
        cout<<b;
    }
    getch();
}

Example 5: Read and write 5 students record in a file using structure. 1

#include<stdio.h>
#include<conio.h>
#include<fstream.h>

struct student
{
    int rollno;
    char name[20];
    int hindi, english, maths, science, sstudies;
    int total;
    float per;
}s[5], s2[5];

int main()
{
    int i;
    FILE *fp;
    clrscr();
    fp=fopen("student.dat","a");
    clrscr();
    for(i=0;i<4;i++)
    {
        printf("Enter student rollno, name and hindi, english, maths, science, sstudies");
        scanf("%d%s%d%d%d%d%d", &s[i].rollno, &s[i].name, &s[i].hindi, &s[i].english, &s[i].maths, &s[i].science, &s[i].sstudies);
        s[i].total=s[i].hindi+s[i].english+s[i].maths+s[i].science+s[i].sstudies;
        s[i].per=s[i].total/5;
        fwrite(&s[i],sizeof(s[i]), 1, fp);
    }
    fclose(fp);

    fp=fopen("student.dat","r");
    printf("Student info:\n");
    for(i=0;i<4;i++)
    {
        fread(&s2[i],sizeof(s2[i]),1,fp);
        printf("Roll no.%d\nName:%s\n", s2[i].rollno, s2[i].name);
        printf("Hindi marks:%d\nEnglish marks:%d\nMaths marks:%d\nScience marks:%d\n;S.Studies marks:%d\n",s2[i].hindi,s2[i].english,s2[i].maths,s2[i].science,s2[i].sstudies);
        printf("\nTotal:%d",s2[i].total);
        printf("\nPercentage:%.2f",s2[i].per);
    }
    fclose(fp);
    getch();
}