C / C++ / MFC

// FD.cpp : Defines the entry point for the console application.
//
 
#include <iostream>
 
using namespace std;
 
long Hex2Int(char * pszHex) {
 
    static unsigned char byteLookup[22][2]  =  
    {   '0', 0, '1', 1, '2', 2, '3', 3, '4', 4, '5', 5, '6', 6, '7', 7, 
        '8', 8, '9', 9, 'A', 10,'B', 11,'C', 12,'D', 13,'E', 14,'F', 15,
        'a', 10,'b', 11,'c', 12,'d', 13,'e', 14,'f', 15
    };
 
    register long total = 0;
 
    int  nPosition = 0;
 
    if(*pszHex) {
 
        register int len = strlen(pszHex) - 1;
 
        while (len >= 0) {
            bool bFound = false;
            int i;
            for (i = 0; i < sizeof(byteLookup)/2; ++i) {
                if(byteLookup[i][0] == *(pszHex+len)) {
                    ++bFound;
                    break;
                }
            }
 
            // didn't find the character in the lookup, so throw.
            if(!bFound) throw "Invalid hex number\n";
 
            if(nPosition == 0) {
                total = byteLookup[i][1];
            }
            else {
                // use left shift to multiply the next value
                total += byteLookup[i][1] << (4 * nPosition);
            }
            
            --len;
            ++nPosition;

            // can only handle up to 32 bits (for this implementation anyway) so throw.
            if (nPosition > 8) throw "Too many hex digits\n";
 
        }
        // here, we could have code to extend the high order bits if the string is < 8 chars
        // and begins with a char/lookup '8' or greater.  The way things work now, you need 
        // to pass an 8 char string starting with '8' or better to get a signed result
        // Any takers???  
 
    }
    else {
        // Empty string was passed in, so throw as well, rather than return 0
        throw "Empty string\n";
    }
 
    return total;
}
 
int main(int argc, char* argv[])
{
    char s[255];
    long result = -1;
 
    while (result) {
        cout << endl << "Enter a hex number please, or 0 to exit: ";
        
        cin >> s;
        
        try {
            result = Hex2Int(s);
            cout << endl << "Hex2Int returned " << dec << result << " [" << hex << result << "]" << endl;
        }
        catch (char * e) {
            cout << e;
        }
    }
 
    return 0;
}

// Formattest.cpp : Defines the entry point for the console application.
//
#include "windows.h"
#include <iostream.h>
#include <strstrea.h>
#include <stdio.h>
 
 
// method 3 (see main)
void OutHex(char c) {
    // set up a buffer
    char buf[8];
 
    // print the char as hex (uppercase) to a buffer...
    sprintf(buf,"%X ", c);
 
    // output the buffer...
    cout << buf;
}
 
 
int main(int argc, char* argv[])
{
 
    char test[] = "Here's some char data";
 
    HANDLE hStdOut = GetStdHandle(STD_OUTPUT_HANDLE);
 
    strstream ss;
 
    DWORD dwBytesWritten;
 
    char *p;
 
    cout << "Method 1:" << endl;
 
    // method 1 - print using cout, with the hex manipulator...
    for ( p = test; *p;  ++p) {
        cout << hex << (int)*p << " ";
    }
 
    
    cout << endl << "Method 2:" << endl;
 
    // method 2 - first print to stream buf, then use WriteConsole...
    for ( p = test; *p;  ++p) {
        ss << hex << (int)*p << " ";
    }
 
    WriteConsole(hStdOut, ss.str(), ss.pcount(), &dwBytesWritten, NULL);
 
 
    cout << endl << "Method 3:" << endl;
 
    // method 3 - use OutHex function
    for ( p = test; *p;  ++p ) {
        OutHex(*p);
    }
 
    // pause...
    int x;
    cin >> x;
 
    return 0;
}