[C++知识库]C语言-16进制字符串和16进制数字转换

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

/**
 * @Brief : 0x01 0x1C 0xA1 0xEF -> "01 1C A1 EF"
 * @param  hex
 * @param  hex_len
 * @param  str
 * @param  str_max
 * @return unsigned short 返回字符串长度
 */
unsigned short hex_to_str(const unsigned char *hex, unsigned short hex_len, char *str,
                          unsigned short str_max)
{
    int j = 0;
    char ascii[] = "0123456789ABCDEF";

    if ((hex == NULL) || (str == NULL))
        return -1;

    if (str_max < (2 * hex_len))
        return -2;

    memset(str, 0, str_max);

    for (int i = 0; i < hex_len; i++, j += 2)
    {
        str[j] = ascii[(hex[i] & 0xF0) >> 4];
        str[j + 1] = ascii[hex[i] & 0x0F];
    }
    return j;

}

/**
 * @Brief : "01 1C A1 EF" -> 0x01 0x1C 0xA1 0xEF
 * @param  str
 * @param  str_len
 * @param  hex
 * @param  hex_max
 * @return unsigned short 返回hex数组长度
 */
unsigned short str_to_hex(const char *str, unsigned short str_len, unsigned char *hex,
                          unsigned short hex_max)
{
    int i = 0;

    if ((hex == NULL) || (str == NULL))
        return -1;

    if (hex_max < (str_len / 2))
        return -2;

    memset(hex, 0, hex_max);

    for (int j = 0; j < str_len; i++, j += 2)
    {
        if (str[j] >= '0' && str[j] <= '9')
        {
            hex[i] = str[j] - '0';
        }
        else if (str[j] >= 'A' && str[j] <= 'F')
        {
            hex[i] = str[j] - 'A' + 10;
        }
        if (j + 1 >= str_len)
        {
            i++;
            break;
        }
        if (str[j + 1] >= '0' && str[j + 1] <= '9')
        {
            hex[i] <<= 4;
            hex[i] |= str[j + 1] - '0';
        }
        else if (str[j + 1] >= 'A' && str[j + 1] <= 'F')
        {
            hex[i] <<= 4;
            hex[i] |= str[j + 1] - 'A' + 10;
        }
    }
    return i;

}

示例：

int main()
{
    unsigned char hex2[100] = {0x01, 0x1C, 0xA1, 0xEF, 0x61, 0x69, 0x64, 0x75};
    char str2[100] = {0};
    char str1[] = "011CA1EF";
    unsigned char hex1[100] = {0};

    int len2 = hex_to_str(hex2, 4, str2, 10);
    printf("len2:%d,%s\r\n", len2, str2);

    int len1 = str_to_hex(str1, 8, hex1, 100);
    printf("len1:%d,%X %X %X %X\r\n", len1, hex1[0], hex1[1], hex1[2], hex1[3]);

    return 0;
}

$main
len2:8,011CA1EF
len1:4,1 1C A1 EF