fgets() in C

fgets() is a standard library function in C that reads a line of text from a specified input stream and stores it in a character array. It is defined in the <stdio.h> header file and provides a safe way to read strings.

• Reads an entire line, including whitespace, until a newline, EOF, or size limit is reached.
• Prevents buffer overflow by limiting the number of characters read, making it safer than gets().

#include <stdio.h>

int main() {
    char buff[100];

    printf("Enter a string:\n");

    // Read input from the user
    fgets(buff, sizeof(buff), stdin);

    printf("You entered: %s", buff);

    return 0;
}

Input

This is Geeks

Output

Enter a string:
This is Geeks
You entered: This is Geeks

Explanation : The fgets() function reads one line of text from stdin and stores it in the character array buff. It continues reading until a newline character (\n), the end of the file (EOF), or the buffer limit is reached. The input is automatically null-terminated, making it safer than gets().

Syntax

fgets(buff, n, stream);

Parameters:

• buff: Pointer to the string buffer where the input will be stored.
• n: The maximum number of characters to read (including the null terminator).
• stream: The input stream, typically stdin for reading from the keyboard.

Return Value:

• Returns the pointer to buff if successful.
• Returns NULL if an error occurs or the end-of-file (EOF) is reached.

Examples of fgets()

The following examples demonstrate how to use the fgets() function in C programs:

Reading from a File

#include <stdio.h>

int main() {
    FILE *fptr = fopen("in.txt", "r");
    
    // Reading the file data using fgets() in the
    // form of a block of size 30 bytes
    char buff[30];
    fgets(buff, sizeof(buff), fptr);
    printf("%s", buff);

    fclose(fptr);
    return 0;
}

Assume that in.txt contains the following data:

The quick brown fox jumps
over the lazy dog.
This sentence contains all letters
of English Alphabets.

Output

The quick brown fox jumps

Reading from Keyboard ( User Input )

#include <stdio.h>
#include <string.h>

int main() {
    char name[20];
    
    printf("Enter your name: \n");
    fgets(name, sizeof(name), stdin);
    
    printf("Hello, %s", name);
    return 0;
}

Output

Enter your name: 
Abhishek      //Entered by user
Hello, Abhishek

gets() vs fgets()

Following table lists the primary differences between the gets() and fgets() functions: