c++/going through vector ends program

aral · 10-11-2006, 10:32 AM

Why does the following code stop after the display of just one "1st for" message ?, so I guess it doesn't even get into that first if ... When I say it stops I mean the process stops with exit value -1. I guess there should be no elements in the vector when it enters in that first for , but why does it stop after exactly one :"1st for" message ?
Do I have to catch any exceptions for std::vector ?

Code:

   
std::vector<KeepAliveMsg> vec;
std::vector<KeepAliveMsg>::iterator p;
for(p=vec.begin();p != vec.end();p++)
{   //a=(*p).pid;
    //b=ob.get_qbuf().pid;
std::cout<<i++<<"."<<" 1st for"<<std::endl;
if( ( (*p).pid)==ob.get_qbuf().pid )
{
std::cout<<i++<<"."<<"wdog before timestamp update"<<std::endl;
(*p).timestamp=ob.get_qbuf().timestamp;
timestamp_changed=true;
}
}//for

if(!timestamp_changed)
		  			{
		  				std::cout<<i++<<"."<<" wdog before push_back in vec"<<std::endl;
						vec.push_back(ob.get_qbuf());
						std::cout<<i++<<"."<<"wdo after push_back in vec"<<std::endl;
						if ( vec.size() != 0 )
							   std::cout<<"Last element: "<<vec.back().pid<<std::endl;
		  			}

xhi · 10-11-2006, 11:34 AM

how about some code tags..

aral · 10-14-2006, 07:53 AM

So how do I put those ?

xhi · 10-14-2006, 10:08 AM

[code]
your code goes in here
[/code]

kev82 · 10-16-2006, 12:34 PM

The code, as you've posted it, shouldn't even loop once. The default constructed vector<KeepAliveMsg> vec is empty so vec.begin()==vec.end(). Hence no loop.

Try and produce the smallest piece of code you can that runs independently (ie we can paste it, compile it, and run it) and produces the error.