字符串和数字相互转换

1. 十六进制字符串转数字

		std::string str = "0xef";
		char c = (char)strtol(str.c_str(), NULL, 16);
		printf("0x%02x
", (unsigned char)c);

结果

2.十六进制数字转字符串

		char c = 0x0e;
		char ch[10] = {0};
		sprintf(ch, "0x%02x", (unsigned char)c);

结果

3. 十六进制输出字符

		char c = 0xa8;
		printf("0x%02x
", (unsigned char)c);

结果

此为标准格式：02保证输出长度为两位、不足补0；(unsigned char)