将字符串转换为十六进制为十六进制 [英] Convert string as hex to hexadecimal

问题描述

我有一个采用uint64_t变量的函数.通常我会这样做:

I have a function that takes an uint64_t variable. Normally I would do this:

irsend.sendNEC(result.value);

result.value是一个uint64_t(十六进制)(我认为).如果我这样做:

result.value is an uint64_t as hexadecimal (I think). If I do this:

String((uint32_t) results.value, HEX)

我明白了:

FF02FD

如果我这样做:

irsend.sendNEC(0x00FF02FD)

它工作得很好，正是我想要的.

it works perfectly and is what I want.

我想把它写成一个字符串(而不是抓住result.value)(因为这就是我从GET请求中得到的).如何将"FF02FD"转换为0x00FF02FD?

Instead of grabbing the result.value, I want to write it as a string (because that's what I get from the GET request). How do I make "FF02FD" into 0x00FF02FD?

也许这使它更容易理解:

Maybe this makes it easier to understand:

GET: http://192.168.1.125/code=FF02FD

//Arduino grabs the FF02FD by doing:

for (int i = 0; i < server.args(); i++) {
  if (server.argName(i) == "code") {
    String code = server.arg(i);
    irsend.sendNEC(code);
  }
}

这是我得到错误的地方:

This is where I get the error:

没有匹配函数可调用'IRsend :: sendNEC(String&)'

no matching function for call to 'IRsend::sendNEC(String&)'

因为:

void sendNEC(uint64_t data, uint16_t nbits = NEC_BITS, uint16_t repeat = 0);

推荐答案

评论内容:

如已经建议的那样，可以使用C标准库函数将包含十六进制值的字符串转换为实际的整数值，例如字符串到无符号长整数"(strtoul)或字符串到无符号长整数长整数"(strtoull).从Arduino类型的String可以使用c_str()成员函数将实际的const char*获取到数据.总而言之，一个十六进制字符串到整数的转换就像

As already suggested, a string containing a hexadecimal value can be converted to an actual integer value using the C standard library functions such as "string to unsigned long" (strtoul) or "string to unsigned long long" (strtoull). From Arduino-type String one can get the actual const char* to the data using the c_str() member function. All in all, one does a hex-string to integer conversion as

uint64_t StrToHex(const char* str)
{
  return (uint64_t) strtoull(str, 0, 16);
}

然后在代码中可以将其称为

Which can then in code be called as

for (int i = 0; i < server.args(); i++) {
  if (server.argName(i) == "code") {
    String code = server.arg(i);
    irsend.sendNEC(StrToHex(code.c_str()));
  }
}

附录:在不同平台上使用int或long时要小心.在具有8位微控制器的Arduino Uno/Nano上，例如ATMega328P，int是int16_t.在32位ESP8266 CPU上，int是int32_t.

Appendum: Be carefull about using int or long on different platforms. On a Arduino Uno/Nano with a 8-bit microcontroller, such as the ATMega328P, an int is a int16_t. On the 32-bit ESP8266 CPU, an int is int32_t.

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