declaring array using non-const variable to id size

[Jim Hudon]

i need to create an array of a size determined by a non-const variable:

int char sampleArray[ arraySize ];

why does the following not work, and what can i do:

const int constArraySize = arraySize;
int char sampleArray[ constArraySize;

for both of the above, i get the same error message when i compile:

"storage size of 'sampleArray' is not constant"

thanks...

[Siemel Naran]

"Jim Hudon" <jd*****@adelph ia.net> wrote in message
news:mKWdneA_NZ dwr1_dRVn-

i need to create an array of a size determined by a non-const variable:

int char sampleArray[ arraySize ];

why does the following not work, and what can i do:

const int constArraySize = arraySize;
int char sampleArray[ constArraySize;

for both of the above, i get the same error message when i compile:

"storage size of 'sampleArray' is not constant"

At present, the size of an array must be a compile time constant. So you
can say

const int constArraySize = 10;
int char sampleArray[ constArraySize ];

What is "int char"?

You can use std::vector though.

std::vector<int > sampleArray(con stArraySize);

[Kai-Uwe Bux]

Jim Hudon wrote:

i need to create an array of a size determined by a non-const variable:

int char sampleArray[ arraySize ];

why does the following not work, and what can i do:

const int constArraySize = arraySize;
int char sampleArray[ constArraySize;

for both of the above, i get the same error message when i compile:

"storage size of 'sampleArray' is not constant"

thanks...

C++ requires that the size of a statically allocated array be known at
compile time.

Your options are:

a) use a dynamically allocated array:

char* sampleArray ( new char [ arraySize ] );

The drawback is that you have to take of memory management yourself.
Therefore, it is probably better to:

b) use std::vector.

#include <vector>
...
std::vector< char > sampleArray ( arraySize );

This will allocate a vector of length arraySize. You can use it almsost as
you would use an array. Upon destruction, memory will be released to the
system automatically.
Best

Kai-Uwe Bux