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The whole concept of code reuse has been trampled upon. And for what??? What advantages does it bring? Here is one line solution:
strtol({HEX_NUMBER_STRING}, NULL, 16)
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unsigned int HexStringToUInt(char* s)
{
unsigned int v = 0;
while (char c = *s++)
{
if (c < '0') return 0; //invalid character
if (c > '9') //shift alphabetic characters down
{
if (c >= 'a') c -= 'a' - 'A'; //upper-case 'a' or higher
if (c > 'Z') return 0; //invalid character
if (c > '9') c -= 'A'-1-'9'; //make consecutive with digits
if (c < '9' + 1) return 0; //invalid character
}
c -= '0'; //convert char to hex digit value
v = v << 4; //shift left by a hex digit
v += c; //add the current digit
}
return v;
}
Most of the branches can be eliminated (and thus any cost of their potentially failed prediction) with 'select' operations, depending on your processor.
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not to beat a dead horse, but if you want to use this rather than some of the slower methods suggested by others, you can eliminate the use of the variable 'firsttime', since it's only used to eliminate shifting (<<4) on the first hex digit. That one shift is probably faster than the test for firsttime (occurs for every digit), and it's OK to shift unconditioinally since shifting those zeros has no affect on the results.
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stringstream ss;
long val;
ss << setbase(16) << "0xFDE8";
ss >> val;
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How beautyful is the Standard Library!!!!!
Thank you, you save me a lot of time (and lines of code... )
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It can also be done like this:
UINT HexToDec(const TCHAR *szValue)
{
UINT iValue;
_stscanf(szValue, _TEXT("%x"), &iValue);
return iValue;
}
I think it's much cleaner and simpler 
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'swscanf' was declared deprecated
you can use also
CString s = _T("1A");
long k = wcstol( _T("0x") + s , 0, 0 );
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what about 0x0000ea64 style?
i try to convert hex string but return 0...
nicekr
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CString hex_num("FDE8");
int dec_num;
sscanf(hex_num,"%x",&dec_num);
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this will also do but it is to slow..
bool CCoder::HexEncode(BYTE*pData,TCHAR*pCode)
{
TCHAR buffer[3];
BYTE b=*pData;
if (b<16)
{
buffer[0]='0';
_itoa(b,buffer+1,16);
}else
_itoa(b,buffer,16);
memcpy(pCode,buffer,2);
return true;
}
bool CCoder::HexDecode(TCHAR*pCode,BYTE*pData)
{
TCHAR nr[3];
BYTE i;
nr[2]='\0';
memcpy(nr,pCode,2);
sscanf(nr,"%x",&i);
*pData=i;
return true;
}
//Spinoza
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It's 2am here. This converter did the trick. I didn't think about strtol either, but i can tell you i chaff at doing cstring.GetBuffer's etc, esp in unicode CE. Thanks for saving me a headache!
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Yep good job, remember that strtol only returns a long so easy to overflow! Change your _httoi to return dword/unsigned long, cheers!
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Thanks Anders, It works !!!!!!!
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I look on the net by 2 hours ago for thsi but I didn't found anything. Then I tried this:
-char Str[]={"0x00f"};
-int n;
-sscanf(Str,"%x",&n);
now n is 15
And work.
So simple. 
for converting a string to int then use atoi forint or atof for float
SilverStar
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You guys ever try strtol.. Check it out.. you didn't have to write anything.
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Nice peace of work. I found it very helpfull. Now can you tell me how can I can I convert a normal string to an integer. I have tried StrToInt but I cant get it to work. I don't know maybe I'm stupid but it says StrToInt Undeclared identifier. Can you help.
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int i = atoi("55");
That does the trick...
- Anders
Money talks, but all mine ever says is "Goodbye!"
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long BinfromHex(CString sz)
{
// This code is used to get the decimal value from given hexadecimal string
long m_nbinVal=0; // stores the decimal value
int cnt=0;
for (int i = sz.GetLength()-1; i>=0; i--)
{
TCHAR psz;
int val;
lstrcpy(&psz,(LPCTSTR)sz.Mid(i,1)); // gets the one by one each character or numeric value and assign the according no
switch (psz)
{
case 'A' :
case 'a' : val = 10;
break;
case 'B' :
case 'b' : val = 11;
break;
case 'C' :
case 'c' : val = 12;
break;
case 'D' :
case 'd' : val = 13;
break;
case 'E' :
case 'e' : val = 14;
break;
case 'F' :
case 'f' : val = 15;
break;
default : val = atoi(&psz);
}
m_nbinVal = m_nbinVal + long(pow(16,cnt) * val); // gets the according decimal value of hexadecimal value
cnt++;
}
return m_nbinVal; // return s the converted value
}
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CString szHex = "FF";
int i = (int)strtol(szHex+'\n',(char **)NULL,16);
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You're using a lookup structure, but with a for() loop to scan through it! This is very inefficient.
If you are already using a lookup, why not go all the way? Create a 256 entry lookup (actually less - you need only to go up to "f"), so, given a character you can do
value = lookup[ch];
Another, more efficient way than you present is:
if (isdigit(ch))
{
value = ch - '0';
}
else
{
value = (ch | 0x20) - 'a' + 10;
}
This is assuming valid input (i.e. no "g"'s in the input, etc.)
-Oz
---
Grab WndTabs from http://www.wndtabs.com to make your VC++ experience that much more comfortable...
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// Convert a hexencode string to a "long" value
// Only pass the hex "digits"...no symbols like "0x..."
static long HexToLong(CString& szHexValue)
{
// Make the string a set of upper case, spaceless values
szHexValue.MakeUpper();
szHexValue.TrimLeft();
szHexValue.TrimRight();
// Convert the digits number to values
long lDigitCount = szHexValue.GetLength();
for (long lDigit=0, lValue=0; lDigit < lDigitCount; ++lDigit)
{
// Make a "space" for the next hex value
lValue *= 16;
// Now convert a single digit to a number
TCHAR cDigit = szHexValue.GetAt(lDigit);
if (cDigit >= '0' && cDigit <= '9')
lValue += cDigit - '0';
else if (cDigit >= 'A' && cDigit <= 'F')
lValue += 10 + cDigit - 'A';
else
throw "Bad digit in Hex value string\nCStringConvert::HexToLong()";
}
return lValue;
}
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You could use std::stringstream, e.g.
const char* str = "0xFF";
std::stringstream stream;
stream << str;
int n;
stream >> std::hex >> n;
assert(n == 255);
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There is a function in c to do that:
#include
long strtol(const char *nptr, char **endptr, int base);
atoi(nptr) does the same as (int) strtol(nptr,(char **)NULL, 10).
so just change the base (10 by 16)
see the man page at: http://www.datafocus.com/docs/man3/strtol.3.asp
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Or sscanf or stringstream set for hex translation or...
There are a million ways to skin this cat.
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