Error Detection Based on Check Digit Schemes

#include "StdAfx.h"

#include <assert.h>

int CharToNumber( TCHAR c )
{    
    switch ( c )
    {
    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': case 'A': return 10;
    case 'b': case 'B': return 11;
    case 'c': case 'C': return 12;
    case 'd': case 'D': return 13;
    case 'e': case 'E': return 14;
    case 'f': case 'F': return 15;
    case 'g': case 'G': return 16;
    case 'h': case 'H': return 17;
    case 'i': case 'I': return 18;
    case 'j': case 'J': return 19;
    case 'k': case 'K': return 20;
    case 'l': case 'L': return 21;
    case 'm': case 'M': return 22;
    case 'n': case 'N': return 23;
    case 'o': case 'O': return 24;
    case 'p': case 'P': return 25;
    case 'q': case 'Q': return 26;
    case 'r': case 'R': return 27;
    case 's': case 'S': return 28;
    case 't': case 'T': return 29;
    case 'u': case 'U': return 30;
    case 'v': case 'V': return 31;
    case 'w': case 'W': return 32;
    case 'x': case 'X': return 33;
    case 'y': case 'Y': return 34;
    case 'z': case 'Z': return 35;    

    default: assert( false );
    }
    return -1;
}

TCHAR NumberToChar( int d )
{
    if( d >=  0  && d <=  9 ) { return d + '0'; }

    if( d >= 10  && d <= 35 ) { return d - 10 + 'A'; }

    return 0x00;
}

int StringToNumber( _tstring s )
{    
	_tistringstream ss( s );

    int n;
    
	ss >> n;

    return n;
}

_tstring NumberToString( int n )
{    
	_tostringstream oss( _tostringstream::out );
    
    oss << n << std::ends;

    return oss.str();
}

/*
_tstring NumberToString( double d )
{    
	_tostringstream oss( _tostringstream::out );
    
    oss.setf(std::ios::fixed);
    oss.precision(4);

    oss << d << std::ends;

    return oss.str();
}
*/