Checking for memory issues

[Ral78]

I'm working on a program that will get a list of words from the user and rearrange it in alphabetical order. So far it works but I think it may have some memory issues because I was testing an alternative way of asking the user how many arrays will be needed other than dynamic memory.

Here is the code:

#include<string>

using namespace std;

int main()
{
    int n; //Used to set the number of arrays of MiString and MiNewString.
    cout << "How many words do you want the list to contain? ";
    cin >> n;

    string MiString[n], MiNewString[n], Temp; //This does work but there may be issues I'm unaware of.
    int i, ii, _Place;

    for (i=0; i<n; i++) //Get the list from the user.
    {
        cout << "Input a word: ";
        cin >> MiString[i];
    }

    for (i=0; i<n; i++) //Alphabetize list
    {
        for (ii=0, _Place=0; ii<n; ii++)
        {
            if (MiString[i] > MiString[ii]) {_Place ++;}
        }
        MiNewString[_Place] = MiString[i];
    }

    cout << "\nYour alphabetized list is:\n";

    for (i=0; i<n; i++) \\Print new list
    {
        cout << MiNewString[i] << "\n";
    }
return 0;
}

If you see any problems with this please tell me.

[jonsca]

When declaring an array, the length must be a constant known at compile time. What you are using here is a language extension for C compilers that allows a "variable-length" array to be defined statically. The downside is that your solution will be non-portable and non-standard as not all compilers support this extension. See http://gcc.gnu.org/onlinedocs/gcc/Variable-Length.html for example.

[thelamb]

A much better (C++) solution would be to move away from C-Style arrays and use a container class like 'vector'.

This will also allow you to use std algorithms like std::sort to sort the vector

[Ral78]

Thanks I'll try that.

[Aranarth]

I'd also like to point out that it's very bad style to declare counter variables outside the for loop, unless you actually need the value the loop stopped at.

[abhimanipal]

@Aranarth

Its a C- style approach. When we are program in C, all the variables have to be declared at the start of the function block

[thelamb]

His approach isn't C-Style as the int i, ii; is not at the start of a scope block.
He does re-use the 'i' in two for loops, which is asking for confusion.

Anyway Ral78 what they are trying to point out is that it is good practice to make a variable's scope as short as possible (do you know what a 'scope' is?). So it is better to write code like:

for( int i = 0; i < n; ++i )
{
   // we can use i here
}
// here we can _not_ use i anymore

for( int i = 0; i < n; ++i )
{
  // Here we can use the new i again
}
// Nope, can't use i anymore

[Ral78]

@ thelamb
Thanks I've forgotten about that. =)