strange problem with dev cpp

**henrychan22** · 06-18-2006

hi whenever i compile my programs with devcpp and then run it i hav this problem where my program ends whenever i press enter after i type in stuff to fill my variable.

for example:

Code:

#include <iostream>
using namespace std;

int main()
{
int num;
cout << "enter a number";
cin >> num;
cout << "the number you enterd is: " << num << endl;
return 0;
}

this program ends right after i enter a value for num. it never gets to the cout statement at the end. this problem is not just specific to that program i just wrote. i have the same problem for every program in which i have to enter a value from the keyboard to fill a variable. could someone tell me how i can fix this problem?

**CondorMan** · 06-18-2006

It will return the value that you entered, but then it will close down immediately. Try running it from the command prompt (Start>Run) or adding the lines

char response;
cin >> response;

immediately before <return 0;>. These are only a couple of ways of achieving what you want.

**bumfluff** · 06-18-2006

You can use
cin.get();
just before resturn although as you have used a cin command you will have to put:

Code:

cin.ignore();
cin.get();

Here is the FAQ entry:
http://faq.cprogramming.com/cgi-bin/...&id=1043284385

**CondorMan** · 06-18-2006

I know about cin.get(), but why is it necessary to have the cin.ignore() before it in this case? I've used it before and not had to have cin.ignore() with it. What's specific about this example?

**bumfluff** · 06-18-2006

It doesn't work properly after using cin >>, or is it that it doesn't work properly after using cin.get(); before it.

**Mario F.** · 06-18-2006

get() leaves the trailing null character on the buffer. Ignore() removes it so that a new get() can operate normally.

**CondorMan** · 06-18-2006

It doesn't work properly after using cin >>, or is it that it doesn't work properly after using cin.get(); before it.

When I just used cin.get(), it didn't pause the console but when I used cin.ignore() before cin.get(), it did pause.

get() leaves the trailing null character on the buffer. Ignore() removes it so that a new get() can operate normally.

Thank you. It's nice to know that something works, but I prefer to know why!

**Tonto** · 06-18-2006

Actually, istream's operator >> leaves a newline ('\n') in the buffer. This is because it is not part of an integer and would not make sense to be converted along with 'num', and so we use ignore() to throw away the newline, and get() to wait for you to press a character. Make sure to keep this fact in mind when you mix input gathering methods like operator >> and getline, because the getline will just eat the newline and return if it's left in the buffer, and confuse the hell out of you.

**whiteflags** · 06-18-2006

The best solution of all is to run your programs in a console window. There are a few reasons that win to do this:

win - you see the output without pausing
win - you can enter parameters easily yourself and actually remember what they are
win - the advantage that you can keep the same window open all the time, make changes, and recompile

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