C++，STL。将带有 rgb 颜色的字符串转换为 3 个 int 值？

Question

字符串看起来像“#123456”，结果应该是:

int r = 0x12;
int g = 0x34;
int b = 0x56;

或者在 c++ 中简单地反转此任务:

How to convert RGB int values to string color

我知道我可以将当​​前字符串拆分为 3 个子字符串，但如何将它们实现为十六进制值？

Answer 1

使用标准库的std::hex:

#include <iostream>
#include <sstream>

int main()
{
   // The hex code that should be converted ...
   std::string hexCode;
   std::cout << "Please enter the hex code: ";
   std::cin >> hexCode;

   // ... and the target rgb integer values.
   int r, g, b;

   // Remove the hashtag ...
   if(hexCode.at(0) == '#') {
      hexCode = hexCode.erase(0, 1);
   }

   // ... and extract the rgb values.
   std::istringstream(hexCode.substr(0,2)) >> std::hex >> r;
   std::istringstream(hexCode.substr(2,2)) >> std::hex >> g;
   std::istringstream(hexCode.substr(4,2)) >> std::hex >> b;

   // Finally dump the result.
   std::cout << std::dec << "Parsing #" << hexCode 
      << " as hex gives (" << r << ", " << g << ", " << b << ")" << '\n';
}