Dynamic allocated arrays

[delpins]

I dynamicly allocated char array with lenght of 30. Then I put x characters int it. Then i dynamicly allocated new char array with lenght of x. I transfered characters from old to new array and when I wanted to print out new array, it printed to me characters from old array as I excepted, and some other unknown characters(like dash). I don't see where is the trouble so I am asking you to help.
Here is the code:
#include <iostream>

using namespace std;

int main()
{
    char *unos=new char[30];
    cin>>unos;
    int x=-1;
    do{
        ++x;
    }while(unos[x]!=0);
    cout<<x<<endl;
    char *ispis=new char[x];
    for(int a=0;a<x;a++){
        ispis[a]=unos[a];
    }
    delete [] unos;
    cout<<ispis<<endl;
    delete [] ispis;
    return 0;
}

Example:

IN: abcd
OUT: abcd-

[ne555]

cout outputs all the character till it find a '\0'
however you are not copying that character (you don't even reserve the space)
So when you try to output it goes out of bounds.

[wasabi]

This shouldn't change anything, since '\0' has an ascii value of 0, but when you're making a end-of-string test, you should compare the character to '\0' (the end-of-string character), not to 0. So, it should be
while(unos[x]!='\0')

As well, as is, your for loop isn't including the end-of-string character. In the example given (abcd), the do-while-loop will end when x=4. Thus, the for-loop will NOT run when a=4. And so, your ispis array will be ['a' 'b' 'c' 'd'] without the end-of-string character, when it SHOULD be ['a' 'b' 'c' 'd' '\0'].

So, changing the for-loop to for(int a=0;a<x+1;a++) should fix it.

[delpins]

It is solved! Thanks for help!

[ne555]

But you need to reserve enough space char *ispis=new char[x+1];

[delpins]

Yes, I have done it. And after copying one space left me free in which I put '/0'. My code now looks like:

#include <iostream>

using namespace std;

int main()
{
    char *unos=new char[30];
    cin>>unos;
    int x=-1;
    do{
        ++x;
    }while(unos[x]!=0);
    cout<<x<<endl;
    char *ispis=new char[x+1];
    for(int a=0;a<x;a++){
        ispis[a]=unos[a];
    }
    ispis[x]='\0';
    delete [] unos;
    cout<<ispis<<endl;
    delete [] ispis;
    return 0;
}

Thanks for help!