C语言如何把该16进制字符转换为ip地址？

Question

我需要把第二个红框内容转换为IP地址，都是string类型，末尾的3B代表着;
能否给予代码参考？感谢

Answer 1

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

/* "AB" -> 0xAB */
int char_to_byte(const char *str_char, unsigned char *str_byte)
{
    unsigned char byte_high = 0x00;
    unsigned char byte_low = 0x00;
    byte_high = *str_char;
    byte_low = *(str_char + 1);

    if ((str_char == NULL) || (str_byte == NULL))
        return -1;

    /* byte High */
    if ((byte_high >= '0') && (byte_high <= '9'))
    {
        byte_high = byte_high - '0';
    }
    else if ((byte_high >= 'a') && (byte_high <= 'f'))
    {
        byte_high = byte_high - 'a' + 0x0a;
    }
    else if ((byte_high >= 'A') && (byte_high <= 'F'))
    {
        byte_high = byte_high - 'A' + 0x0a;
    }
    else
    {
        return -1;
    }

    /* byte Low */
    if ((byte_low >= '0') && (byte_low <= '9'))
    {
        byte_low = byte_low - '0';
    }
    else if ((byte_low >= 'a') && (byte_low <= 'f'))
    {
        byte_low = byte_low - 'a' + 0x0a;
    }
    else if ((byte_low >= 'A') && (byte_low <= 'F'))
    {
        byte_low = byte_low - 'A' + 0x0a;
    }
    else
    {
        return -1;
    }

    *str_byte = (byte_high << 4) + byte_low;
    return 0;
}

/* "ABCD..." -> [0xAB, 0xCD, ...] */
int hex_str_convert(const char *str_in, char *str_out)
{
    int i = 0;
    unsigned char tmp = 0;
    size_t len = strlen(str_in);

    for (i = 0; i < len / 2; i++)
    {
        if (char_to_byte(&str_in[i * 2], &tmp) == 0x00)
            *(str_out + i) = tmp;
        else
            return -1;
    }

    return 0;
}

int main()
{
    char str_out[64] = { 0 };
    const char *str_in = "3131372E37342E3133362E33343B";

    hex_str_convert(str_in, str_out);
    printf(str_out);

    return 0;
}

• 运行输出: 117.74.136.34;