linux itoa()

在 Linux 中，itoa() 函数通常不是标准库函数，因此需要自行实现。

下面是一个简单的实现：

#include <stdio.h>
#include <stdlib.h>

char *itoa(int num, char *str, int base)
{
    int i = 0, isNegative = 0;

    /* Handle 0 explicitly */
    if (num == 0) {
        str[i++] = '0';
        str[i] = '\0';
        return str;
    }

    /* Handle negative numbers */
    if (num < 0 && base == 10) {
        isNegative = 1;
        num = -num;
    }

    /* Process individual digits */
    while (num != 0) {
        int rem = num % base;
        str[i++] = (rem > 9) ? (rem - 10) + 'a' : rem + '0';
        num /= base;
    }

    /* If number is negative, append '-' */
    if (isNegative)
        str[i++] = '-';

    str[i] = '\0'; /* Append string terminator */

    /* Reverse the string */
    int j, len = i;
    for (i = 0, j = len-1; i < j; i++, j--) {
        char temp = str[i];
        str[i] = str[j];
        str[j] = temp;
    }

    return str;
}

使用示例：

int main()
{
    int num = -123;
    char str[12];
    itoa(num, str, 10);
    printf("%s\n", str);
    return 0;
}

输出：`-123`