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c++arraysglobal
Leigh K
Leigh K

Reputation: 603

2D Global Array Error - Array Bound Is Not An Integer Constant

I can't seem to find an answer to this. I realize that the integer value used in an array must be known at compile time, and what I have here seems to meet that criteria. If I use:

int L = 50;                     // number of interior points in x and y

int pts = L + 2;                // interior points + boundary points
double  u[pts][pts],            // potential to be found
    u_new[pts][pts];            // new potential after each step

Then I get the array bound error, even though the value for pts is known at compile time. The code is accepted, however, when I use:

int L = 50;                     // number of interior points in x and y

int pts = L + 2;                // interior points + boundary points
double  u[52][52],              // potential to be found
    u_new[52][52];              // new potential after each step

Am I missing something here? If not, what can I do to have it accept pts?

Upvotes: 2

Views: 62

Answers (1)

R Sahu
R Sahu

Reputation: 206577

When you use

int L = 50;
int pts = L + 2;

L and pts cannot be used as dimensions of arrays since they are not compile time constants. Use constexpr qualifiers to let the compiler know that they can be computed at compile time, and hence can be used as dimensions of arrays.

constexpr int L = 50;
constexpr int pts = L + 2;

Upvotes: 3

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