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Old Jul 10, 2010, 12:45 PM   #1
Danksalot
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C++ - Having trouble with cin >> in xCode...

I am using xCode on a Mac to write some c++ code.

Any time I use cin >> the program compiles just fine, but when I run it something happens that I didn't expect. I enter what I want for input and hit the RETURN key, and it goes to the next line, waiting for me to type something else. As far as I know, it should stop looking for input at that point, but it doesn't. Here's an example:


Code:
#include <iostream>
 
using namespace std;
 
int main()
    {
    int Num = 0;
    cout << "Enter a number: " << endl;
    cin >> Num;
    cout << "You entered: " << Num << endl;
    return 0;
    }
I never get to the "You entered: " statement, because I can't get it to assign the dang input! Anybody who knows what's going on, please let me know. Here's what the program looks like running:

Enter a number:
5
15
2546


x
b
5



No matter what I enter, when I hit the RETURN key, it just goes to the next line and waits. Thanks in advance for any help!

Danksalot
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Old Jul 10, 2010, 12:50 PM   #2
Matthew Yohe
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Works here.

Have you updated XCode lately?
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Old Jul 10, 2010, 01:06 PM   #3
Danksalot
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I just checked and I'm running xCode 3.1.4 on Leopard.

Looks like I'll have to get Snow Leopard to update any farther.

Last edited by Danksalot; Jul 10, 2010 at 01:20 PM.
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Old Jul 10, 2010, 01:10 PM   #4
Matthew Yohe
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Quote:
Originally Posted by Danksalot View Post
I just checked and I'm running xCode 3.1.4 on Leopard.

I'll update to the latest version, then give it a try.
That's the latest version for Leopard. You need to update to Snow Leopard.
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Old Jul 10, 2010, 01:13 PM   #5
chown33
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A specific problem with C++ streams, in Xcode debugger, Debug build.
Fix is to undefine Preprocessor Macros = _GLIBCXX_DEBUG=1 _GLIBCXX_DEBUG_PEDANTIC=1

http://forums.macrumors.com/showpost.php?p=8590820
.. the specific problem and fix.

Threads that discuss problem and fix:
http://forums.macrumors.com/showthread.php?t=867839
http://forums.macrumors.com/showthread.php?t=863761
http://forums.macrumors.com/showthread.php?t=837748
http://forums.macrumors.com/showthread.php?t=796818
http://forums.macrumors.com/showthread.php?t=780440
.. 867839 lists specific steps to take.
.. 796818 notes input problems.
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Old Jul 10, 2010, 01:16 PM   #6
Matthew Yohe
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I should've just searched here for that problem. I was Googling for Espinosa's thread on the XCode mailing list.
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Old Jul 10, 2010, 02:32 PM   #7
Danksalot
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I had success locating those files, and I deleted them, and it still does not work. The program still runs exactly as I have described above. I also tried using #undef in my program to no avail.

Is there any way that I deleted them in the Edit Active Target menu and it didn't actually take them out?

Any other ideas?

I really appreciate your time and expertise!

Danksalot

Last edited by Danksalot; Jul 10, 2010 at 02:38 PM.
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Old Jul 10, 2010, 02:52 PM   #8
chown33
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File > New Project
Command Line Utility, C++ Tool

Edit main.cpp
I copy and paste your source code exactly.
Save.

"Debug" is active build configuration.
Build > Build. It builds.

Run > Run.
It runs.
It prompts "Enter a number:".
I press 5.
Press Return.
It prints "You entered: 5"
It exits.

Run > Run.
It runs.
It prompts "Enter a number:".
I press 5.
Press Enter. <--- DIFFERENT
Nothing.
Press Enter again.
Nothing.
Key in 33.
Press Return.
It prints "You entered: 33"
It exits.

Xcode 3.1.4. OS 10.5.8. Mac mini with Core 2 Duo.


Questions:
Are you hitting Return or Enter?
Are you running with Run or Debug?
Which build configuration?
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Old Jul 10, 2010, 10:41 PM   #9
Danksalot
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I guess I thought I was using the RETURN key, but I was using the ENTER key every time. That solved my problem. Thanks a heap!

Danksalot
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