🔴 Advanced · Lesson 36

File Handling in C

File Handling

File handling allows a C program to store data permanently in files and read it later. C uses FILE pointer and functions from stdio.h.

Function	Use
`fopen()`	Open file
`fclose()`	Close file
`fprintf()`	Write formatted data
`fscanf()`	Read formatted data
`fgets()`	Read a line
`fputs()`	Write a string

File Modes

Mode	Meaning
`r`	Open existing file for reading
`w`	Create/overwrite file for writing
`a`	Append data at end
`r+`	Read and write existing file
`w+`	Read and write, overwrite/create
`a+`	Read and append

Write File

C Language

#include <stdio.h>

int main() {
    FILE *fp = fopen("students.txt", "w");
    if(fp == NULL) {
        printf("File cannot be opened");
        return 1;
    }

    fprintf(fp, "Roll Name Marks\n");
    fprintf(fp, "101 Aman 89\n");
    fprintf(fp, "102 Riya 94\n");

    fclose(fp);
    printf("Data written successfully");
    return 0;
}

Read File

C Language

#include <stdio.h>

int main() {
    FILE *fp = fopen("students.txt", "r");
    char line[100];

    if(fp == NULL) {
        printf("File not found");
        return 1;
    }

    while(fgets(line, sizeof(line), fp) != NULL) {
        printf("%s", line);
    }

    fclose(fp);
    return 0;
}

Summary

Use FILE * for file operations
Always check if fopen() returns NULL
Close every opened file using fclose()
Use correct mode: read, write or append
Use text functions for simple text files

File Handling

File handling से C program data को permanently files में store और later read कर सकता है। इसके लिए stdio.h के functions use होते हैं।

File Modes

Mode	Meaning
`r`	Read existing file
`w`	Write/overwrite
`a`	Append
`r+`	Read + write
`w+`	Read + write, overwrite

File Write

C Language

FILE *fp = fopen("data.txt", "w");
if(fp == NULL) {
    printf("File error");
    return 1;
}
fprintf(fp, "Hello File");
fclose(fp);

File Read

C Language

FILE *fp = fopen("data.txt", "r");
char line[100];
while(fgets(line, sizeof(line), fp) != NULL) {
    printf("%s", line);
}
fclose(fp);

सारांश

File handling permanent data storage देती है
FILE * pointer use होता है
fopen() के बाद NULL check करें
काम पूरा होने पर fclose() करें
Mode सही choose करें

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