42-libft/ft_strncmp.c at master · Kjur0/42-libft · GitHub

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/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   ft_strncmp.c                                       :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: kjurkows <kjurkows@student.42warsaw.pl>    +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2026/06/16 14:21:22 by kjurkows          #+#    #+#             */
/*   Updated: 2026/06/29 23:37:44 by kjurkows         ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */

#include "libft.h"
//# Part 1
//## string manipulation

/** @brief compare two strings
 *
 * compares only first non-matching character.
 * operates on ASCII codes
 *
 * @param s1	first string
 * @param s2	second string
 * @param n		max length for comparison
 * @return		difference between first unmatched chars
 * @retval 0	no difference
 */
int	ft_strncmp(const char *s1, const char *s2, size_t n)
{
	const unsigned char	*str1 = (const unsigned char*)s1;
	const unsigned char	*str2 = (const unsigned char*)s2;
	size_t				i;

	i = 0;
	if (!s1 && s2)
		return (-str2[i]);
	if (!s2 && s1)
		return (str1[i]);
	if (!s1 && !s2)
		return (0);
	while ((str1[i] || str2[i]) && i < n)
	{
		if (str1[i] != str2[i])
			return (str1[i] - str2[i]);
		i++;
	}
	return (0);
}