StringFormat hex output parameters... how to convert from hex to uchar or string

[Wemerson Guimaraes]

Hi... i am looking at documentation of CryptEncode function and there are a good example code... there are a function ArrayToEx that converts a uchar array to a Hexadecimal string... using StringFormat and "%.2X" as the output parameter.

Well, i need to know how to do the opposite: Fill an uchar array using an hexadecimal string... Here an example of converting my name to hex:

//+------------------------------------------------------------------+
//|                                                        ToHex.mq4 |
//|                                         Wemerson Couto Guimaraes |
//+------------------------------------------------------------------+
#property copyright "Wemerson Couto Guimaraes"
#property link      ""
#property version   "1.00"
#property strict

// Simple script to convert a value to be represented in hexadecimal

//+------------------------------------------------------------------+
//| Script program start function                                    |
//+------------------------------------------------------------------+
void OnStart()
  {
      string myname="Wemerson";
      uchar arr[];
      StringToCharArray(myname, arr);
      
      string hex=ArrayToHex(arr);
      
      printf("My Name: %s in Hex is: %s", myname, hex);
   
  }
//+------------------------------------------------------------------+

string ArrayToHex(uchar &arr[],int count=-1)
  {
   string res="";
//--- check
   if(count<0 || count>ArraySize(arr))
      count=ArraySize(arr);
//--- transform to HEX string
   for(int i=0; i<count; i++)
      res+=StringFormat("%.2X",arr[i]);
//---
   return(res);
  }

The result is:

2017.10.11 10:40:47.411 ToHex EURUSD,H1: My Name: Wemerson in Hex is: 57656D6572736F6E00

Now i waht to convert the hex value 57656D6572736F6E00 to the string represented by this hex string...

[William Roeder]

Wemerson Guimaraes: Now i waht to convert the hex value 57656D6572736F6E00 to the string represented

So what's stopping you?

Not compiled, not tested.

string long_to_hex(ulong value){
   string result="";
   do{
      result = string(value & 0xF)+result;
      value >>= 8;
   }while(value != 0);
   return result;
}

Not compiled, not tested.

Was that so hard?

[Wemerson Guimaraes]

whroeder1:

So what's stopping you?

Thank you for your support... Well... i found how to convert an string to an string containing the HEX chars... as i show in my example... but What is istopping me is is that i don't know how to do the inverse... convert a string containing HEX chars back to the original string.... 

whroeder1:

Was that so hard?

Yep for me it's hard, this is the reason i came here looking for help! If my knowlegment was so extense like yours i believe i will not need to beg for help here... 

About your suggestion, it is for converting a numeric value to hexadecimal right ? Well, converting to HEX i know how to do using uchar array and StringFormat output parameter "%.2X"... but i need to to the opposite...  

[William Roeder]

Wemerson Guimaraes: it is for converting a numeric value to hexadecimal right ? Well, converting to HEX i know how to do using uchar array and StringFormat output parameter "%.2X"... but i need to to the opposite...  

1. Converting a numeric to a hex string, I gave you.
2. A uchar array and a string are the same thing, different formats.
3. You need "the opposite" of what? Show us your attempt and state the nature of your problem.
             No free help
             urgent help.

[Wemerson Guimaraes]

whroeder1:

1. Converting a numeric to a hex string, I gave you.
2. A uchar array and a string are the same thing, different formats.
3. You need "the opposite" of what? Show us your attempt and state the nature of your problem.
             No free help
             urgent help.

I found exactly what i need here: Joao Rosas hexToInteger function

Thank you for your appointments. Your the best my friend!

[Doerk Hilger]

static char __hex [] = { '0', '1', '2', '3', '4', '5', '6', '7',
                        '8', '9' ,'A', 'B', 'C', 'D', 'E', 'F' };
string IntegerToHexString(uint num)
{
   int len=0,k=0;
   char buff[64];
   do
      {
      uint n=num&0xF;
      buff[len] = __hex[n];
      len++;
      num>>=4;
      }
   while(num!=0);
   
   for(;k<len/2;k++)
      {
      buff[k]^=buff[len-k-1];
      buff[len-k-1]^=buff[k];
      buff[k]^=buff[len-k-1];
      }
   return CharArrayToString(buff,0,len);
}

Unfortunately the static var __hex cannot be inside the function as a local static variable, because it will not be intialized correctly. MQ supports this is normal, but it´s not, it´s a bug of the compiler.