fgets() in C

fgets() is a built-in function in <stdio.h> used to read a line of text from input.

• It stores the input into a character array and stops reading when it reaches a newline character, the specified number of characters, or end-of-file (EOF).
• It is safer than gets() because it prevents buffer overflow by limiting the number of characters read.
• We can use it to read a full line (including whitespace) from input, rather than stopping at the first space like scanf("%s", …) would.

#include <stdio.h>

int main() {
    char buff[100];  
    int n = 10;
  
    printf("Enter a string: \n");
  
    // Read input from the user
    fgets(buff, n, stdin);
    printf("You entered: %s", buff);
    return 0;
}

Output

Enter a string: 
This is Geeks     {entered by user}
You entered: This is Geeks

Explanation : In this program, fgets() reads will read up to 9 characters or until a newline (\n) is encountered from the standard input (stdin) and stores them in the array buff, ensuring it is null-terminated.

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: