Actual combat String Series in C + +--16 binary string to hexadecimal integer (usually color code used)

It's been a long time since I wrote a blog about string. Because the writing almost the same. But the recent deal with string, so the hormone of the brain, small tadpoles restless.

In the program, assume that the use of color code, is generally hexadecimal, that is, Hex.

But the server returns you a color string. That is, hex string

How do you convert this hex string to hex and use it in your code?

Further, how do you convert a hex string, such as "#ffceed", to RGB?

The first question in Java is this:

 Public Static int Parsecolor(@Size(min=1) String colorstring) {if(Colorstring.charat (0) ==' # ') {//Use a long to avoid rollovers on #ffXXXXXXLongcolor = Long.parselong (colorstring.substring (1), -);if(colorstring.length () = =7) {//Set the alpha valueColor |=0x00000000ff000000;}Else if(Colorstring.length ()! =9) {Throw NewIllegalArgumentException ("Unknown Color");}return(int) color;}Else{Integer color = scolornamemap.Get(Colorstring.tolowercase (Locale.root));if(Color! =NULL) {returnColor;}}Throw NewIllegalArgumentException ("Unknown Color");}

In C + +, however, we can use the flow, which is more concise:

 auto Color_string_iter = Hex_string_color.begin  ()     Hex_string_color.erase  (color_string_iter)     hex_string_color=  "FF"  + hex_string_color;     DWORD color;     std :: StringStream ss;     SS << std :: Hex << hex_string_color;     SS >> std :: Hex >> color;     Btn1->setbkcolor (color)  Btn2->setbkcolor (0xff123456 )   

There is another way to use: Std::strtoul
is primarily the third parameter:
Numerical base (radix) that determines the valid Characters and their interpretation.
If This is 0, the base used are determined by the format of the sequence

#include <cstdlib>#include <iostream> // for std::coutint main(){    char"0xbeef";    unsignedlong hex_value        std016);    std::cout"hex value: "std::endl;    return0;}

Next look at how to turn hex string RGB:

#include <iostream>#include <sstream>intMain () {STD::stringHexcode;STD::cout<<"Please enter the hex code:";STD::Cin>> Hexcode;intR, G, B;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::d EC <<"Parsing #"<< Hexcode <<"as Hex gives ("<< R <<", "<< g <<", "<< b <<")"<<' \ n ';}

Here is a bit of advice and advice.
We start with learning programming, and the most familiar is print or cout to see the results. But in the actual work is very rarely used.

For example, there is a decimal number 100. Why we passed cout<

Actual combat String Series in C + +--16 binary string to hexadecimal integer (usually color code used)