在Arduino中将（逗号分隔的十六进制）字符串转换为无符号char数组

Question

The response payload of my http request looks like this (but can be modified to any string best suitable for the task):

"{0X00,0X01,0XC8,0X00,0XC8,0X00,
0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,}"

How do I turn it into an unsigned char array containing the hex values like this:

unsigned char gImage_test[14] = { 0X00,0X01,0XC8,0X00,0XC8,0X00,
0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,}

Additional information: The length of the payload string is known in advance and always the same. Some partial solution I found can't be directly applied due to the limitations of the wrapper nature of Arduino for c++. Looking for a simple solution within the Arduino IDE.

Answer 1

Use sscanf("%x", ...) , here an example of just 3 hex numbers:

const char *buffer = "{0X00,0X01,0XC8}";
unsigned int data[3];
int read_count = sscanf(buffer, "{%x,%x,%x}", data, data+1, data+2);
// if successful read_count will be 3

Answer 2

If using sscanf() ( #include <stdio.h> ) is within your limitations then you can call with it "%hhx" to extract each individual hex value into an unsigned char like this:

const int PAYLOAD_LENGTH = 14; // Known in advance
unsigned char gImage_test[PAYLOAD_LENGTH];

#include <stdio.h>

int main()
{
    const char* bufferPtr = "{0X00,0X01,0XC8,0X00,0XC8,0X00,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF,0XFF}";
    for (int i = 0; i < PAYLOAD_LENGTH && sscanf(bufferPtr + 1, "%hhx", &gImage_test[i]); i++, bufferPtr += 5);

    return 0;
}