实现将十六进制字符串转换为字节数组

c实现 - 

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>unsigned char* hexStringToByteArray(const char* hex_str, size_t* out_len) {size_t len = strlen(hex_str);size_t byte_count = 0;// 计算实际的十六进制字符数（忽略空格）for (size_t i = 0; i < len; ++i) {if (isxdigit(hex_str[i])) {++byte_count;}}// 必须是偶数个十六进制字符if (byte_count % 2 != 0) {fprintf(stderr, "Invalid hex string: odd number of hex digits.\n");*out_len = 0;return NULL;}// 分配字节数组*out_len = byte_count / 2;unsigned char* byte_array = (unsigned char*)mal