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Hey,
I'm a beginning C++ programmer and I'm writing a console file-search application that uses a DataBase with a list of files (like locate from the linux shell). Below is the sourcecode that I've written so far. I'm posting it here because I don't know any good programmers myself and I would really like to get some tips and comments to push me in the right direction.

Besides that, I've also got a few specific questions:

1)
The inline function UnDefBit sets a bit to zero by doing the following:
lineofbits = ((2^32)-1 - 2^bitnumber) AND lineofbits.
I was wondering if there is an easier way to do this because this seems kind of time-consuming to me, and I'd rather not load the math.h library.

2)
Someone told me that I should use a DWORD for storing rows of bits. Why should I use a DWORD instead of a long int?

Code:

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#include <windows.h>
#include <iostream.h>
#include <math.h>

DWORD OptionFlags = 0;

inline bool BitTrue(DWORD a, DWORD b) { return (a & (1 << b)) ? true : false; } //Is bit 1?
inline void DefBit(DWORD &a, DWORD b) { a = (a | (1 <<  b)); } //define bit
inline void UnDefBit(DWORD &a, DWORD b) { a = DWORD(4294967295 - pow(2, b)) & a; } //undefine bit


DWORD LogicDrives(bool HDsOnly) //All Logical drives or Harddisks only
{       
        DWORD DriveList = GetLogicalDrives();
       
        if (HDsOnly)
        {
                char DriveCheck[4] = "*:\\";
                for (int a = 0; a < 26; a++)
                {       
                        if (BitTrue(DriveList, a))
                        {
                                DriveCheck[0]= 'a'+a;
                                UnDefBit(DriveList, a);
                                if (GetDriveType(DriveCheck)==3) DefBit(DriveList, a); //Check if it's a HD
                        }
                }
        }
       
        return DriveList;
}


DWORD DrivesFromArgs(int argc, char *argv[]) //Drives from arguments
{
        DWORD DriveList = 0;
        char DrivesString[26];

        for (int a = 1; a < argc; a++) //Get DrivesString from arguments
        {
                        if (argv[a][0] == '/' && argv[a][1] == 'd')
                        {
                                        strcpy(DrivesString, argv[a + 1]);
                                        break;
                        }
        }

        for (a = 0; a < 26; a++) //Create DriveList from DrivesString[]
        {
                        if (DrivesString[a] >= 'a' && DrivesString[a] <= 'z') DefBit(DriveList, DrivesString[a] - 'a');
                        else break;
        }

        return DriveList;
}


DWORD Options(int argc, char *argv[]) //Get Options from arguments
{       
        DWORD Flags=0;
        for(int a = 1; a < argc; a++)
        {
                if (argv[a][0] == '/')
                {
                        switch (argv[a][1])
                                {
                                        case 'c': DefBit(Flags, 0); break; //Create DB
                                        case 'v': DefBit(Flags, 1); break; //Verbose mode
                                        case 'd': DefBit(Flags, 2); break; //Specified drives in args
                                        case 'a': DefBit(Flags, 3); break; //All logical drives
                                }
                }
        }
        return Flags;
}


void Say(int LineNum, int a=0, DWORD Flags=0) //Output a line
{
        int b = 0;

        switch (LineNum) //will always be said
        {
                case 0: cout << "Start of program" << endl; return;
                case 1: cout << "End of program" << endl; return;
        }
       
       
        if (BitTrue(OptionFlags, 1)) //will only be said in verbose mode
        {
                switch (LineNum)
                {
                        case 100: cout << a << " arguments: "; for(;b < 10;b++) cout << BitTrue(Flags, b); cout << endl; return;
                        case 101: cout << "Creating database" << endl; return;
                        case 102: cout << "Drives to index: "; for(;b < 26;b++) cout << BitTrue(Flags, b); cout << endl; return;
                }
        }
}


void CreateDatabase(int argc, char *argv[]) //Creates a database
{
        Say(101);
        DWORD DrivesToIndex;
               
        if (BitTrue(OptionFlags, 2)) DrivesToIndex = DrivesFromArgs(argc, argv); //Get drives from arguments
        else if (BitTrue(OptionFlags, 3)) DrivesToIndex = LogicDrives(false); //Do All logic drives
        else DrivesToIndex = LogicDrives(true); //Do all HDs
       
        Say(102,0,DrivesToIndex);
}


int main(int argc, char *argv[]) //main
{
        Say(0);       
        OptionFlags = Options(argc, argv); //get options
        Say(100, argc-1, OptionFlags);
        if (BitTrue(OptionFlags, 0)) CreateDatabase(argc, argv);
        Say(1);
        return 0;
}

---

Thanks for the help!

Add another function

Code:

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inline DWORD Bit(pos) { return 1ul << pos; }                // A bit in the right pos
inline bool BitTrue(DWORD a, DWORD b) { return (a & Bit(b)) != 0; } //Is bit 1?
inline void DefBit(DWORD &a, DWORD b) { a |= Bit(b); }      //define bit
inline void UnDefBit(DWORD &a, DWORD b) { a &= ~Bit(b); }  //undefine bit

---

> Someone told me that I should use a DWORD for storing rows of bits. Why should I use a DWORD instead of a long int?
Except DWORD is currently specified in windows.h (which not everyone has)

Besides, its a rather generic type. You would be better with say
typedef unsigned long bits_t;
Which conveys a bit more meaning for what is going on, and is more portable to other platforms.

Man I feel stupid about my way of writing down a &= ~Bit(b)

thanks...