fgets() and gets() in C

In C, fgets() and gets() are functions used to read strings from input streams. The key difference is that fgets() is safe and checks array bounds, while gets() is unsafe and has been removed from C11 standard due to buffer overflow vulnerabilities.

fgets() Function

The fgets() function reads a string from a specified stream until a newline character or the specified limit is reached −

Syntax

char *fgets(char *string, int size, FILE *stream);

Parameters:

• string − Pointer to character array where the string will be stored
• size − Maximum number of characters to read (including null terminator)
• stream − Input stream (commonly stdin for standard input)

Example

#include <stdio.h>
#define MAX_SIZE 50

int main() {
    char buffer[MAX_SIZE];
    
    printf("Enter a string: ");
    fgets(buffer, MAX_SIZE, stdin);
    
    printf("You entered: %s", buffer);
    return 0;
}

Enter a string: Hello TutorialsPoint
You entered: Hello TutorialsPoint

gets() Function (Deprecated)

The gets() function reads a string from standard input but does not check array bounds, making it vulnerable to buffer overflow attacks. It has been removed from C11 standard.

Syntax

char *gets(char *string);  // DEPRECATED - DO NOT USE

Safe Alternative to gets()

Instead of using gets(), use fgets() with stdin −

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

int main() {
    char text[100];
    int i;
    
    printf("Enter a string: ");
    fgets(text, sizeof(text), stdin);
    
    // Remove newline character if present
    text[strcspn(text, "<br>")] = '\0';
    
    // Convert to uppercase
    for (i = 0; text[i] != '\0'; i++) {
        if (text[i] >= 'a' && text[i] <= 'z') {
            text[i] = text[i] - 32;
        }
    }
    
    printf("String in Upper Case: %s<br>", text);
    return 0;
}

Enter a string: hello world
String in Upper Case: HELLO WORLD

Comparison

Key Points

• Always use fgets() instead of gets() for safe string input
• fgets() includes the newline character in the string; use strcspn() to remove it
• The size parameter in fgets() should be the actual size of the buffer

Conclusion

fgets() is the recommended function for reading strings in C due to its buffer overflow protection. Never use gets() as it poses serious security risks and has been deprecated.