Please chk this ther is some error?

[vjshankwar]

Hi all,

i create this code for some conversion but i dont know waht is the mistake is present dere,
loop is not return,

please chk this code.

//here i pass

Value=72;
digits=7;

CString PDU::Bin(int Value, short digits)
{
	CString Bin;
	//#define def_Bin
//#ifdef def_Bin

	CString result; 
	short exponent=0;
     // this is faster than creating the string by appending chars
     result = CString("0"[0],32);
	 do{
		 if (Value & Power2(exponent)) {
             // we found a bit that is set, clear it
             result.Mid(32 - exponent-1, 1);
             Value = Value ^ Power2(exponent);
		 }
         exponent += 1;
	 } while (Value);
	 if (digits < 0) {
         // trim non significant digits, if digits was omitted or negative
         Bin = result.Mid(33 - exponent-1);
	 } else {
         // else trim to the requested number of digits
         Bin = result.Right(digits);
	 }

//#endif // def_Bin

	return Bin;

}
int PDU::Power2(int exponent)
{
	int Power2=0;

//#define def_Power2
//#ifdef def_Power2

	 static int res[31+1];
     int I;

     // rule out errors
     if( exponent < 0 || exponent > 31) /*throw(5);*/
		 //AfxMessageBox("Invalid");

     // initialize the array at the first call
	 if(res[0] = 0) {
         res[0] = 1;
		 for(I = 1;I<30;I++) {
             res[I] = res[I - 1] * 2;
		 }
         // this is a special case
         res[31] = 0x80000000;
	 }

     // return the result
     Power2 = res[exponent];

//#endif // def_Power2


	return Power2;

}

please help me.

[Skizmo]

i create this code for some conversion but i dont know waht is the mistake is present dere,

Would be nice if you told us what the problem is.

[VictorN]

It would also be nice if you:

1. removed all unnecessary comments (like commented out lines of code)
2. explained what CString("0"[0],32) means

[Skizmo]

result = CString("0"[0],32);

Is the same as...

CString ('0', 32);

Value = Value ^ Power2(exponent);

^ is a bitwise XOR, not 'power'.

[VictorN]

result = CString("0"[0],32);

Is the same as...

CString ('0', 32);

Wow! Thank you, Skizmo!
I usually prefer very simple and short expression, so this one:

CString ('0', 32);

I like better!

[jeron]

loop is not return,

Does this mean that the do..while loop never exits?

Using the debugger and stepping through the code (in the do..while loop) should point you to the problem fairly quickly.

[VictorN]

I'd also recommend to not use CString in this algorithm at all (note, that it won't work in the UNICODE build, and you could have some problems because of multiple NULL-characters in it). Use CByteArray instead!