[2 days left] Whatâ€™s wrong with your cloud strategy? Learn why multicloud solutions matter with Nimble Storage.Register Now

x
Solved

# Buffer to integers

Posted on 2003-10-28
Medium Priority
491 Views
Hi,
I have a buffer which contains hex numbers

e.g ff 22 5f 4f 4f ff 4a 6a aa ff 9a 9b af .....etc

I want to copy each of the hex numbers from the buffer in turn, to an integer.
i.e.
int numa = 0xff;
int numb = 0x22;
int numc = 0x5f;
int numd = 0x4f;
int nume = 0x4f; ...and so forth

I need the code to be efficient please,

Thanks
John
0
Question by:XPUSR
[X]
###### Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

• Help others & share knowledge
• Earn cash & points
• 2
• 2
• 2
• +2

LVL 2

Expert Comment

ID: 9637329
This buffer is a array of hex numbers? or is a string?

Post the declaration of that buffer please.

0

Author Comment

ID: 9637502
----------------------------------
char * buffer;
buffer = (char*) malloc (10000);
fgets ( buffer, 1000,"file.txt" );
-------------------------------------
the buffer is a string of hex values(without the 0x) "ff 22 5f 4f 4f ff 4a 6a aa ff 9a 9b af ". These values are taken from a text file "file.txt" and copied to the buffer.

sorry for being so ambiguous...

J
0

LVL 19

Assisted Solution

Dexstar earned 300 total points
ID: 9637764
XPUSR:

> I want to copy each of the hex numbers from the buffer in turn, to an integer.

Try this:

int GetHexValue( char chr )
{
switch( toupper(chr) )
{
case '0': return 0x00;      break;
case '1': return 0x01;      break;
case '2': return 0x02;      break;
case '3': return 0x03;      break;
case '4': return 0x04;      break;
case '5': return 0x05;      break;
case '6': return 0x06;      break;
case '7': return 0x07;      break;
case '8': return 0x08;      break;
case '9': return 0x09;      break;
case 'A': return 0x0A;      break;
case 'B': return 0x0B;      break;
case 'C': return 0x0C;      break;
case 'D': return 0x0D;      break;
case 'E': return 0x0E;      break;
case 'F': return 0x0F;      break;
default:  return 0;            break;
}
}

// lpszChars = Array of Chars to Convert
// pInts = Array of Ints to Hold Converted Values
// nSize = # of Ints to Convert
void ConvertHex( char* lpszChars, int* pInts, size_t nSize )
{
char*      lpCurrent = lpszChars;

for ( unsigned register nCounter = 0 ; nCounter < nSize ; ++nCounter )
{
pInts[nCounter] = (GetHexValue(*(lpCurrent++)) << 8) |
GetHexValue(*(lpCurrent++));
}
}

Just allocate the array of integers that you want to convert, and then ConvertHex().

Hope that helps,
Dex*
0

LVL 15

Expert Comment

ID: 9638446
Or you could let the library do more of the work:

#include <sstream>

using namespace std;

istringstream iss(buffer);
// Tell iss to interpret numbers as hexadecimal.
iss.setf(ios::hex, ios::basefield);

iss >> numa;
iss >> numb;
//  etc.

--efn
0

LVL 3

Accepted Solution

EarthQuaker earned 300 total points
ID: 9638754
Developping efn's path of stopping wheel's reinvention :

#include <algorithm>
#include <sstream>
#include <vector>

const char* buffer="ff 22 5f 4f 4f ff 4a 6a aa ff 9a 9b af";
istringstream ss(buffer);
ss >> hex;
vector<int> v;
copy(istream_iterator<int>(ss), istream_iterator<int>(), back_inserter(v));

cout << "Item 1 is " << v[0] << endl;
0

LVL 19

Expert Comment

ID: 9643280
Well, those are good too... I just wanted to give him a solution where it was very clear what was going on and how it worked.  You start invoking the STL like that on someone who doesn't know it, and they will find it difficult to learn how you did what you did.

Dex*
0

LVL 3

Expert Comment

ID: 9644031
Dex : Nothing wrong with your solution, it's prolly faster.

I just tend to use something premade & robust & fast instead of doing all by hand.
0

Author Comment

ID: 9708505
Thanks both solutions work 100%, appreciate that you were trying to explain it....

John
0

## Featured Post

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Programmer's Notepad is, one of the best free text editing tools available, simply because the developers appear to have second-guessed every weird problem or issue a programmer is likely to run into. One of these problems is selecting and deletiâ€¦
Basic understanding on "OO- Object Orientation" is needed for designing a logical solution to solve a problem. Basic OOAD is a prerequisite for a coder to ensure that they follow the basic design of OO. This would help developers to understand the bâ€¦
The viewer will learn how to use and create keystrokes in Netbeans IDE 8.0 for Windows.
The viewer will learn how to clear a vector as well as how to detect empty vectors in C++.
###### Suggested Courses
Course of the Month15 days, left to enroll