👨‍💻
Guide
Laura's GithubSimon's Github
  • What is this gitbook for?
  • 🛠️Useful tools
    • 🏁Header files
    • 🧱C Structures
    • 🔗Linked Lists (todo)
    • 📄Makefiles
    • 🔄Switch statement
    • 🗃️File descriptors (FD)
  • 🖌️MiniLibX
    • MiniLibX Helper Function
    • MiniLibX Hook Examples
  • 0️⃣ Rank 00
    • Libft
      • 📑LIBC functions
        • ft_isalpha
        • ft_isdigit
        • ft_isalnum
        • ft_isascii
        • ft_isprint
        • ft_strlen
        • ft_memset
        • ft_bzero
        • ft_memcpy
        • ft_memmove
        • ft_strlcpy
        • ft_strlcat
        • ft_toupper
        • ft_tolower
        • ft_strchr
        • ft_strrchr
        • ft_strncmp
        • ft_memchr
        • ft_memcmp
        • ft_strnstr
        • ft_atoi
        • ft_calloc
        • ft_strdup
      • 📑Additional functions
        • ft_substr
        • ft_strjoin
        • ft_strtrim
        • ft_split
        • ft_itoa
        • ft_strmapi
        • ft_striteri
        • ft_putchar_fd
        • ft_putstr_fd
        • ft_putendl_fd
        • ft_putnbr_fd
      • 📑Bonus functions
        • ft_lstnew
        • ft_lstadd_front
        • ft_lstsize
        • ft_lstlast
        • ft_lstadd_back
        • ft_lstdelone
        • ft_lstclear
        • ft_lstiter
        • ft_lstmap
  • 1️⃣ Rank 01
    • Born2beRoot
      • 📠What's a virtual machine ?
      • 📠Install your virtual machine
      • 📠P2P Evaluation - Questions
    • ft_printf
      • ▪️Variadic functions
      • ▪️Building the thing
    • get_next_line
      • ▪️open() & read()
      • ▪️Static variables
      • ▪️Building the thing
      • ▪️Commented solution
  • 2️⃣ Rank 02
    • so_long
      • ▪️Understand so_long
      • ▪️Core concepts
      • ▪️Building the thing
    • pipex
      • ▪️Understand pipex
      • ▪️Functions used
      • ▪️Building the thing
    • minitalk
      • ▪️Understand minitalk
      • ▪️Functions used
      • ▪️Building the thing
    • push_swap
      • ▪️Algorithms
      • ◾Building the thing
    • FdF
      • 🗡️Understand FdF
      • 🗡️Graphics programming
      • 🗡️Building the thing
  • 3️⃣ RANK 03
    • Philosophers
      • ▪️Understand Philosophers
      • ▪️Functions used
      • ▪️Building the thing
    • Minishell
      • ▪️Understand Minishell
      • ▪️Functions
      • ◾Building the thing
  • 4️⃣ RANK 04
    • CPP (00 - 04) (doing)
      • CPP00
      • CPP01
      • CPP02
      • CPP03
      • CPP04 (doing)
    • NetPractice
      • Theory
      • Level 1 & 2
    • MiniRT
      • Understand MiniRT
      • Building the thing
  • 5️⃣ RANK 05
    • CPP (05-09) (to-do)
      • CPP05
      • CPP06 (to-do)
      • CPP07
      • CPP08 (to-do)
      • CPP09 (to-do)
    • Inception (doing)
      • 🕓The basics (Docker, Images, etc...)
      • Project Files
    • webserv (to-do)
  • 6️⃣ rank 06
    • ft_transcendence (to-do)
  • 🛂Exams
    • Exam Rank 02
      • Level 1
        • first_word
        • fizz_buzz
        • *ft_putstr
        • *ft_strcpy
        • *ft_strlen
        • ft_swap
        • repeat_alpha
        • rev_print
        • rot_13
        • rotone
        • search_and_replace
        • ulstr
      • Level 2
        • alpha_mirror
        • camel_to_snake
        • do_op
        • *ft_atoi
        • *ft_strcmp
        • ft_strcspn
        • ft_strspn
        • *ft_strdup
        • ft_strpbrk
        • ft_strrev
        • inter
        • last_word
        • ft_is_power_2
        • max
        • print_bits
        • reverse_bits
        • wdmatch
        • swap_bits
        • union
        • snake_to_camel
      • Level 3
        • add_prime_sum
        • epur_str
        • expand_str
        • ft_atoi_base
        • ft_list_size
        • ft_range
        • ft_rrange
        • hidenp
        • lcm
        • paramsum
        • pgcd
        • print_hex
        • rstr_capitalizer
        • str_capitalizer
        • tab_mult
      • Level 4
        • flood_fil
        • fprime
        • ft_split
        • ft_itoa
        • ft_list_foreach
        • ft_list_remove
        • rev_wstr
        • rotstring
        • sort_int_tab
        • sort_list
    • Exam Rank 03
    • Exam Rank 04
    • Exam Rank 05
      • Module 0
  • 👥Team
Powered by GitBook
On this page
  • Subject
  • Understandable explanation
  • Hints
  • Commented solution

Was this helpful?

  1. 0️⃣ Rank 00
  2. Libft
  3. LIBC functions

ft_strncmp

Subject

STRNCMP(3) (simplified)

NAME
    strncmp -- compare strings
SYNOPSIS
    int strncmp(const char *s1, const char *s2, size_t n);
DESCRIPTION
    The strncmp() function lexicographically compare the null-terminated strings s1 and s2.
    The strncmp() function compares not more than n characters. Because strncmp() is designed for comparing strings rather than binary data, characters that appear after a '\0' character are not compared.
RETURN VALUES
    The strncmp() function returns an integer greater than, equal to, or less than 0, according as the string s1 is greater than, equal to, or less than the string s2. The comparison is done using unsigned characters, so that '\200' is greater than '\0'.

Understandable explanation

strncmp() compares string in a lexicographic order, this means that it compares each characters by their corresponding ASCII values.

strncmp() compares maximum n characters in both strings.

The returned value depends on what difference is found. If the two strings are the same, the returned result will be 0 since there is no difference.

If there is a difference, and the first different character in s2 is greater than the character at the same place in s1, the returned result will be negative.

If there is a difference, and the first different character in s2 is less than the character at the same place in s1, the returned result will be positive.

Hints

ft_strncmp.c
int ft_strncmp(const char *s1, const char *s2, size_t n)
{
    /* loop over both string until we reach n characters */
    /* check if current s1 character is different than
     * current s2 character
     */
         /* if characters are different, return the difference
          * between both characters
          */
      /* if we read both strings until n characters and no difference
       * were found, return 0 as there is no difference
       */
}

Commented solution

ft_strncmp
ft_strncmp.c
#include "libft.h"

int ft_strncmp(const char *s1, const char *s2, size_t n)
{
    size_t i;
    
    i = 0;
    while ((s1[i] || s2[i]) && i < n)
    {
        if ((unsigned char) s1[i] != (unsigned char) s2[i])
            return ((unsigned char) s1[i] - (unsigned char) s2[i]);
        i++;
    }
    return (0);
}
Previousft_strrchrNextft_memchr

Last updated 2 years ago

Was this helpful?

📑