Create and destroy an object in a loop

Question

I am new to C++/stacko and want to principally:

Create an object
Read in an enormous amount of data for that
After calculating that object's score, print it out
Delete the object from memory because each object has a lot of variables attributed to it
Loop it 1000 times

It seems simple enough but after looking around I see things about destructors but I don't know if that's what I am looking for.

for(int i=0; i<1000; i++){
    applicants object1;
    object1.readin();
    cout<<object1.calculate();
    //How do I delete object1 and start again?
}

Thank you so much for any help. I don't know hardly anything about this language. Also, do I even need objects? I'm confused

The code so far is good. At the end of the block (the loop body) your `object1` is destroyed, i.e. its destructor is invoked. Mostly that's automatic, and if you use e.g. `std::vector` for your data you don't have think about it. — Cheers and hth. - Alf, Feb 21 '15 at 21:22
Your object are created on the stack hence will destruct automatically once it's goes out of the scope, which happens after each loop. — meirm, Feb 21 '15 at 21:22
Unless he is using a pointer to dynamic memory. You should better give us the declaration of 'applicants'. — AnArrayOfFunctions, Feb 21 '15 at 21:27
You couldn't be bothered to write out "Stack Overflow" in full?! — Lightness Races in Orbit, Feb 21 '15 at 22:54
@LightnessRacesinOrbit Can I be a part of the cool guys now? — Script Kitty, Feb 22 '15 at 01:27

score 3 · Accepted Answer · answered Feb 21 '15 at 21:22

3

It is not necessary to delete object1.

For every iteration of the loop, a new object object1 will be created (using default constructor) and destructed after the "cout" statement.

answered Feb 21 '15 at 21:22

Rob

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3

This is true because the object is directly on the stack, not allocated on the heap with a pointer (via `new`). Objects made with `new` need to be `delete`d. – StilesCrisis Feb 21 '15 at 21:24

score 3 · Answer 2 · edited May 23 '17 at 12:17

You don't need to call the destructor of object1, it would be called at the end of the loop body.

Technically, destructors are called at the end (right brace) of the block declaring the object.

This is why the right brace } is sometimes jokingly called the most important statement in C++. A lot of things may happen at that time.

It is however generally considered bad style to do real computations in constructors or destructors. You want them to "allocate" and "deallocate" resources. Read more about RAII and the rule of five (or of three).

BTW, if an exception happens, the destructors between the throw and the matching catch are also triggered.

Please learn more about C++ containers. You probably want your applicants class to use some. Maybe it should contain a field of some std::vector type.

Also learn C++11 (or C++14), not some older version of the standard. So use a recent compiler (e.g. GCC 4.9 at least, as g++, or Clang/LLVM 3.5 at least, as clang++) with the -std=c++11 option (don't forget to enable warnings with -Wall -Wextra, debugging info with -g for debugging with gdb, but enable optimizations e.g. with -O2 at least, when benchmarking). Modern C++11 (or C++14) has several very important features (missing in previous standards) that are tremendously useful when programming in C++. You probably should also use make (here I explain why), see e.g. this and others examples. See also valgrind.

score 2 · Answer 3 · answered Feb 21 '15 at 21:22

Object one will be deleted automatically when it goes out of scope at the end bracket. You are already doing it. Be wary as if you create a pointer it will not be destructed when it goes out of scope. But your current code is working fine.

http://www.tutorialspoint.com/cplusplus/cpp_variable_scope.htm

Create and destroy an object in a loop

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