dynamic array problem

rockstar_212

I tried to use dynamic array. but it gives me following error
Project Project1.exe raised exception class EInvalidPointer with message 'Invalid pointer operation'
after that when i click continue it gives next error
Project Project1.exe raised exception class EStackOverflow with message 'Stack overflow'.
now next message is access voilation at xxxxxx
so where i am going wrong?
Heres my source code

int sizeofx;
sizeofx=StrToInt(ComboBox1->Text);
int* x=NULL; // Pointer to int, initialize to nothing.
x = new int[sizeofx]; // Size needed for array
int sizeofpsp;
sizeofpsp=npsp;
int* psp=NULL;
psp = new int[sizeofpsp];
int k=0; //Counter
int temp; //To store value of 2's complement
int l;
l=sizeofx;
int loc1=StrToInt(Edit4->Text);
int loc2=StrToInt(Edit5->Text);
/////////////////////////////////////////
for(k=1;k<=sizeofx;k++)
{
x[k]=1;
}

/////////////////////////////////////////
for(k=1;k<=sizeofpsp;k++)
{
psp[k]=x[sizeofx];
temp=x[loc1]^x[loc2];
do
{
x[l]=x[l-1];
l--;
}while(l>1);
x[1]=temp;
l=sizeofx;

}
///////////////////////////////////////////////
for(k=0;kCells[k][0]=psp[k+1];
}

delete [] x; // When done, free memory pointed to by x.
//x = NULL; // Clear a to prevent using invalid memory reference.
delete [] psp; // When done, free memory pointed to by psp.
//psp = NULL; // Clear a to prevent using invalid memory reference.

bilderbikkel

: I tried to use dynamic array. but it gives me following error
: Project Project1.exe raised exception class EInvalidPointer with message 'Invalid pointer operation'
You write/read out of the array's bounds.

I'd suggest to use code tags next time [leftbr]code] and [leftbr]/code]

Arrays go from index 0 to [b]and not including[/b] their size.
So an array of size x has indices 0 to x.

[code]
: for(k=1;k<=sizeofx;k++)
: for(k=1;k<=sizeofpsp;k++)
[/code]

Your for-loops also rad/write at index x (one beyond the max index).

Why not use a std::vector, it can do range checking for you?

You might want to check
www.codepedia.com/1/CppArray
www.codepedia.com/1/CppVector

See ya,
bilderbikkel

rockstar_212

: : I tried to use dynamic array. but it gives me following error
: : Project Project1.exe raised exception class EInvalidPointer with message 'Invalid pointer operation'
: You write/read out of the array's bounds.
:
: I'd suggest to use code tags next time [leftbr]code] and [leftbr]/code]
:
: Arrays go from index 0 to [b]and not including[/b] their size.
: So an array of size x has indices 0 to x.
:
: [code]
: : for(k=1;k<=sizeofx;k++)
: : for(k=1;k<=sizeofpsp;k++)
: [/code]
:
: Your for-loops also rad/write at index x (one beyond the max index).
:
: Why not use a std::vector, it can do range checking for you?
:
: You might want to check
: www.codepedia.com/1/CppArray
: www.codepedia.com/1/CppVector
:
: See ya,
: bilderbikkel
It show error while closing program. function works correctly means it gives correct results. and when i change dynamic array to static array it doesnt shows any error.
well i have never tried vector thing. will be interesting .

bilderbikkel

: It show error while closing program. function works correctly means it gives correct results. and when i change dynamic array to static array it doesnt shows any error.
Yes, this error is not always detected.
Both code snippets below are equally wrong:

[code]
const int size = 5;
int array[size];
array[size] = 0; //ERROR! Out of range!
[/code]

[code]
const int size = 5;
int * array = new int[size];
array[size] = 0; //ERROR! Out of range!
[/code]

Access violations are viewed as 'time bombs'. If YOU don't get them NOW, does not mean that you or someone else will get it.

: well i have never tried vector thing. will be interesting .
It is recommended to do so by the Experts.

Compare this:
[code]
const int size = 5;
std::vector v(size);
const int index = size;

if (index < 0 || index >= v.size()) //Yes, bigger or equal then the size
{
std::cout << "OUT OF RANGE!!!" << std::endl;
}

v[index] = 0; //ERROR! Out of range!
[/code]

See ya,
bilderbikkel

rockstar_212

: Access violations are viewed as 'time bombs'. If YOU don't get them NOW, does not mean that you or someone else will get it.
:
: : well i have never tried vector thing. will be interesting .
: It is recommended to do so by the Experts.
:
: Compare this:
: [code]
: const int size = 5;
: std::vector v(size);
: const int index = size;
:
: if (index < 0 || index >= v.size()) //Yes, bigger or equal then the size
: {
: std::cout << "OUT OF RANGE!!!" << std::endl;
: }
:
: v[index] = 0; //ERROR! Out of range!
: [/code]
:
: See ya,
: bilderbikkel

thanks 4 help
its always good to see u here

bilderbikkel

I forgot to mention that the std::vector has an [b]at[/b] method that can do range checking for you:

[code]
const int size = 5;
std::vector v(size);
v.at(size) = 0; //Will give an error
v.at( -1) = 0; //Will give an error
[/code]

See ya,


bilderbikkel