Programming Forums > Application Development > C++

grumpy · Jan 19th, 2008, 4:01 PM

Quote:

Originally Posted by pcbrainbuster

Also could Grumpy please tell me what the abbreviation stands for?

RTFM = Read The Fine Manual

If you want to learn, it is better to put some time into reading readily available documentation (eg on MSDN in your case) and putting in effort to understand it, rather than asking others to provide you with canned answers.

In practice, some people attach different words to one or two letters of the RTFM abbreviation to more strongly emphasise the message. I'll leave it to you to find out examples of that for yourself.

pcbrainbuster · Jan 19th, 2008, 5:44 PM

I'm currently feeling the direct opposite of Sane right now

I'm even more confused then I was before.

Questions -
1) American Dragon mensioned that 'it' doesn't even return true or false. Well, if that is the case, then isn't it like saying that the statement is always true(I know that this has no chance of being true(what I said) though)? Please expand on this.

2) This is a optional question; It never really hit me but I've seen people do something like "if(hWnd) ...", what does this check or compare exactly?

Sorry for all the questions

, thanks.

grumpy · Jan 19th, 2008, 7:18 PM

Quote:

Originally Posted by pcbrainbuster

1) American Dragon mensioned that 'it' doesn't even return true or false. Well, if that is the case, then isn't it like saying that the statement is always true(I know that this has no chance of being true(what I said) though)? Please expand on this.

Actually, the Dragon is Ancient.

Roughly speaking, the construct "if (x)" tests if x is non-zero. Any non-zero value will be detected as true, and only zero tests as false. So the test "if (x)" is equivalent to "if (x != 0)".

Quote:

Originally Posted by pcbrainbuster

2) This is a optional question; It never really hit me but I've seen people do something like "if(hWnd) ...", what does this check or compare exactly?

It tests if hWnd is non-zero. Since window handles are implemented as pointers, and there is an incidental rule that setting a pointer to zero has the same effect as setting it to NULL, the test "if (hWnd)" is shorthand for "if (hWnd != NULL)".

pcbrainbuster · Jan 20th, 2008, 7:37 AM

Lol, I got him confused with one of the cartoons in this country

Here are a couple more questions :
1) Are 0, false and NULL the same?
2) Is any number other then 0 the same as true?

Thanks!

grumpy · Jan 20th, 2008, 8:03 AM

Quote:

Originally Posted by pcbrainbuster

1) Are 0, false and NULL the same?

No; if you look they are typed differently.

0 is an integer value of zero. false is a keyword. NULL is an implementation-defined null pointer value.

They can be converted to each other in some contexts. For example, (int)false yields a value of 0.

Quote:

Originally Posted by pcbrainbuster

2) Is any number other then 0 the same as true?

(int)true has a value of 1 if that's what you mean.

Sane · Jan 20th, 2008, 11:23 AM

Sometimes the best way to understand something is to try and see for yourself...

For example, try running this. Look at the output. Notice how all if statements evaluate as True, except for those with == true. Only an integer of 1, as Grumpy pointed out, will be equal to true.

(Toggle Plain Text)

#include <iostream>
using namespace std;

void eval(bool x) {
    if(x) cout << "Is True\n";
    else  cout << "Is False\n";
}

void experiment(int x, int y) {
    cout << (x) << " & " << (y) << " = " << (x & y) << "\n\n";
    
    eval(x);
    eval(y);
    eval(x & y);
    eval(x & y == y);
    eval(x & y != 0);
    eval(x & y != false);
    eval(x == true);  
    eval(y == true);
    eval(x & y == true);
}

int main() {
    // 13 is 00001101
    //  4 is 00000100
    experiment(13, 4);
    return 0;
}

pcbrainbuster · Jan 20th, 2008, 12:46 PM

Thanks to you all for your great help!

RESOLVED

Cache · Jan 20th, 2008, 5:56 PM

Sane, the code below is broken. Due to the higher precedence of operator == over operator & your code actually evaluates to (x & (y == y)). I think your intention was ((x & y) == y). This goes for the other operators you used too.

(Toggle Plain Text)

eval(x & y == y);

Sane · Jan 20th, 2008, 6:12 PM

Oh shoot. Thank-you for the correction. Conveniently, the output is no different.

(Toggle Plain Text)

#include <iostream>
using namespace std;

void eval(bool x) {
    if(x) cout << "Is True\n";
    else  cout << "Is False\n";
}

void experiment(int x, int y) {
    cout << (x) << " & " << (y) << " = " << (x & y) << "\n\n";
    
    eval(x);
    eval(y);
    eval(x & y);
    eval((x & y) == y);
    eval((x & y) != 0);
    eval((x & y) != false);
    eval(x == true);  
    eval(y == true);
    eval((x & y) == true);
}

int main() {
    // 13 is 00001101
    //  4 is 00000100
    experiment(13, 4);
    return 0;
}

Jan 19th, 2008, 5:44 PM	#12
pcbrainbuster Programmer Join Date: Dec 2007 Posts: 93 Rep Power: 1	Re: GetWindowInfo - I'm currently feeling the direct opposite of Sane right now I'm even more confused then I was before. Questions - 1) American Dragon mensioned that 'it' doesn't even return true or false. Well, if that is the case, then isn't it like saying that the statement is always true(I know that this has no chance of being true(what I said) though)? Please expand on this. 2) This is a optional question; It never really hit me but I've seen people do something like "if(hWnd) ...", what does this check or compare exactly? Sorry for all the questions , thanks.

Jan 20th, 2008, 7:37 AM	#14
pcbrainbuster Programmer Join Date: Dec 2007 Posts: 93 Rep Power: 1	Re: GetWindowInfo - Lol, I got him confused with one of the cartoons in this country Here are a couple more questions : 1) Are 0, false and NULL the same? 2) Is any number other then 0 the same as true? Thanks!

Jan 20th, 2008, 11:23 AM	#16
Sane Programming Guru Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 1,886 Rep Power: 5	Re: GetWindowInfo - Sometimes the best way to understand something is to try and see for yourself... For example, try running this. Look at the output. Notice how all if statements evaluate as True, except for those with `== true`. Only an integer of 1, as Grumpy pointed out, will be equal to `true`. (Toggle Plain Text) #include <iostream> using namespace std; void eval(bool x) { if(x) cout << "Is True\n"; else cout << "Is False\n"; } void experiment(int x, int y) { cout << (x) << " & " << (y) << " = " << (x & y) << "\n\n"; eval(x); eval(y); eval(x & y); eval(x & y == y); eval(x & y != 0); eval(x & y != false); eval(x == true); eval(y == true); eval(x & y == true); } int main() { // 13 is 00001101 // 4 is 00000100 experiment(13, 4); return 0; } #include <iostream> using namespace std; void eval(bool x) { if(x) cout << "Is True\n"; else cout << "Is False\n"; } void experiment(int x, int y) { cout << (x) << " & " << (y) << " = " << (x & y) << "\n\n"; eval(x); eval(y); eval(x & y); eval(x & y == y); eval(x & y != 0); eval(x & y != false); eval(x == true); eval(y == true); eval(x & y == true); } int main() { // 13 is 00001101 // 4 is 00000100 experiment(13, 4); return 0; }

Jan 20th, 2008, 12:46 PM	#17
pcbrainbuster Programmer Join Date: Dec 2007 Posts: 93 Rep Power: 1	Re: GetWindowInfo - Thanks to you all for your great help! RESOLVED

Jan 20th, 2008, 5:56 PM	#18
Cache Hobbyist Join Date: Sep 2005 Posts: 261 Rep Power: 4	Re: GetWindowInfo - Sane, the code below is broken. Due to the higher precedence of operator == over operator & your code actually evaluates to (x & (y == y)). I think your intention was ((x & y) == y). This goes for the other operators you used too. (Toggle Plain Text) eval(x & y == y); eval(x & y == y);

Jan 20th, 2008, 6:12 PM	#19
Sane Programming Guru Join Date: Apr 2005 Location: Waterloo, Ontario Posts: 1,886 Rep Power: 5	Re: GetWindowInfo - Oh shoot. Thank-you for the correction. Conveniently, the output is no different. (Toggle Plain Text) #include <iostream> using namespace std; void eval(bool x) { if(x) cout << "Is True\n"; else cout << "Is False\n"; } void experiment(int x, int y) { cout << (x) << " & " << (y) << " = " << (x & y) << "\n\n"; eval(x); eval(y); eval(x & y); eval((x & y) == y); eval((x & y) != 0); eval((x & y) != false); eval(x == true); eval(y == true); eval((x & y) == true); } int main() { // 13 is 00001101 // 4 is 00000100 experiment(13, 4); return 0; } #include <iostream> using namespace std; void eval(bool x) { if(x) cout << "Is True\n"; else cout << "Is False\n"; } void experiment(int x, int y) { cout << (x) << " & " << (y) << " = " << (x & y) << "\n\n"; eval(x); eval(y); eval(x & y); eval((x & y) == y); eval((x & y) != 0); eval((x & y) != false); eval(x == true); eval(y == true); eval((x & y) == true); } int main() { // 13 is 00001101 // 4 is 00000100 experiment(13, 4); return 0; }

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Programming Forums > Application Development > C++

GetWindowInfo -