Help with Hex To Int
Author
How do I convert a 2 character string such as '1F' and convert it into an integer? I looked around at a listing of the standard functions, but I didn't see anythign that appeared to do this. :S
Quote:Original post by Vampyre_DarkTry strtoul, it allows you to specify the integer's base.
How do I convert a 2 character string such as '1F' and convert it into an integer? I looked around at a listing of the standard functions, but I didn't see anythign that appeared to do this. :S
int result = strtoul(string, NULL, 16);
I think std::hex can be used to read/write hexidecimal numbers from streams in C++, and scanf should work in C.
Oh, strtol. I should have thought of that, I used to use that a lot.
Oh, strtol. I should have thought of that, I used to use that a lot.
Author
Okay, Thanks alot. I did this... it compiles, but I won't be able to test it until the rest of my map parser is done. :)
//grab the ambient color
//and convert the hex value back
//to 3 floats
fMap.get(ca,2); //alpha
fMap.get(ca,2); //r
m_LightAmbient[0] = ((float)strtoul(ca,NULL,16) /255);
fMap.get(ca,2); //g
m_LightAmbient[1] = ((float)strtoul(ca,NULL,16) /255);
fMap.get(ca,2); //b
m_LightAmbient[2] = ((float)strtoul(ca,NULL,16) /255);
fMap.get(ca,256,';');
//grab the ambient color
//and convert the hex value back
//to 3 floats
fMap.get(ca,2); //alpha
fMap.get(ca,2); //r
m_LightAmbient[0] = ((float)strtoul(ca,NULL,16) /255);
fMap.get(ca,2); //g
m_LightAmbient[1] = ((float)strtoul(ca,NULL,16) /255);
fMap.get(ca,2); //b
m_LightAmbient[2] = ((float)strtoul(ca,NULL,16) /255);
fMap.get(ca,256,';');
I just wrote my own function:
That's just off the top of my head though.
BYTE FromHex(char ch){ switch(tolower(ch)) { case '0': return 0; case '1': return 1; case '2': return 2; case '3': return 3; case '4': return 4; case '5': return 5; case '6': return 6; case '7': return 7; case '8': return 8; case '9': return 9; case 'a': return 10; case 'b': return 11; case 'c': return 12; case 'd': return 13; case 'e': return 14; case 'f': return 15; default: return 0; }}BYTE FromHex(char ch1, char ch2){ return (FromHex(ch1)<<4) | FromHex(ch2);}That's just off the top of my head though.
Because I have a large hammer and like to use it to pound small nails:
#include <boost/spirit.hpp>#include <iostream>#include <string>using namespace std;using namespace boost::spirit;int main ( void ){ string hex="1F"; unsigned int value; parse( hex.c_str() , hex_p[assign_a(value)] ); //converts to native number cout << "Decimal value: " << value << endl; //cout defaults to decimal string buffer; getline( cin , buffer );}
Couldn't you just typecast it?
int HexValue = (int)CharString;
I've tried assigning hex values to ints and it just 'translates' them for you.
int Value = 0xF;
Makes Value == 15.
int HexValue = (int)CharString;
I've tried assigning hex values to ints and it just 'translates' them for you.
int Value = 0xF;
Makes Value == 15.
Nope. Then hexvalue would contain the address of the string (as that is what is stored in CharString).
Note the difference between:
int Value = 0xF;
and
int Value = (int)"0xF";
Note the difference between:
int Value = 0xF;
and
int Value = (int)"0xF";
Here's how I did it. Hopefully the code works, 'cause I didn't test it recently...just pulled it from an old project.
hexToInt is the one you want
typedef unsigned char UCHAR;typedef unsigned int UINT;char hexToNibble(char n){ assert( (n >= '0') && (n <= '9') || (n >= 'A') && (n <= 'F') || (n >= 'a') && (n <= 'f') ); // make sure it's a hex digit! if ( (n >= '0') && (n <= '9') ) return( n & 0x0F ); if ( (n >= 'A') && (n <= 'F') ) return( n - 55 ); if ( (n >= 'a') && (n <= 'f') ) return( n - 87 ); return 0; // should never be here assuming assert worked in debug mode}UCHAR hexToByte(const char *b){ return (UCHAR)((hexToNibble(b[0]) << 4) | hexToNibble((b[1])));}int hexToInt (const char *s){ int j = 0; char *p = (char *)s; while (*p) { j <<= 4; j |= hexToNibble(*(p++)); } return j;}hexToInt is the one you want
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