ft_itoa.c

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/* ************************************************************************** */
/*                                                                            */
/*                                                        :::      ::::::::   */
/*   ft_itoa.c                                          :+:      :+:    :+:   */
/*                                                    +:+ +:+         +:+     */
/*   By: kfujita <kfujita@student.42tokyo.jp>       +#+  +:+       +#+        */
/*                                                +#+#+#+#+#+   +#+           */
/*   Created: 2022/04/18 06:34:36 by kfujita           #+#    #+#             */
/*   Updated: 2022/04/26 00:14:13 by kfujita          ###   ########.fr       */
/*                                                                            */
/* ************************************************************************** */
 
#include "ft_string.h"
#include <stdlib.h>
 
#define NUM_STR_BUF_LEN (12)
 
static char *reverse_str(char *str)
{
    char    *str_top;
    char    *str_end;
    char    tmp;
 
    if (str == NULL)
        return (NULL);
    str_top = str;
    str_end = str;
    while (*str_end != '\0')
        str_end++;
    str_end -= 1;
    while (str_top < str_end)
    {
        tmp = *str_end;
        *str_end-- = *str_top;
        *str_top++ = tmp;
    }
    return (str);
}
 
static long ft_absl(long v)
{
    if (v >= 0)
        return (v);
    else
        return (v * -1);
}
 
char    *ft_itoa(int n)
{
    char    num_str_buf[NUM_STR_BUF_LEN];
    int     buf_pos;
    long    long_n;
 
    if (n == 0)
        return (ft_strdup("0"));
    buf_pos = 0;
    long_n = ft_absl(n);
    while (long_n != 0)
    {
        num_str_buf[buf_pos++] = (long_n % 10) + '0';
        long_n /= 10;
    }
    if (n < 0)
        num_str_buf[buf_pos++] = '-';
    num_str_buf[buf_pos] = '\0';
    return (reverse_str(ft_strdup(num_str_buf)));
}