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

I haven't written a blog about string for a long time. Because it's almost written. But lately he's been dealing with string, and then he's got a brain, and a little tadpole is restless.

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

But the server returns you a color string, the 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");}

But in C + +, we can use streams, 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 )   

Another way, you can 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 to 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, the most familiar is print or cout look at the results. But it is seldom used in practical work. For example, there is a decimal number 100, how do we pass cout<

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