I'm writing a class in C++. I need to create a member 2d array but the size is not known until the constructor is called... Currently, in my header I have defined the array: int* i2d; and in the constructor it's initialised: i2d = new int[width][height]; width and height are parameters passed into the constructor. All I get with this is a compiler error 'error C2540: non-constant expression as array bound' using MSVC++6 (no MFC). It works fine if I create it as: i2d = new int[width * height]; which will give me the same number of elements, but I really need it to be 2d... Any ideas?? TIA

uh... Why can't you use the latter method? That's the way people usually create 2d arrays.. You could always create a macro: #define MAX_WIDTH 32 #define I2DMACRO(w,h) w*MAX_WIDTH+h ... i2d[I2DMACRO(width,height)]=12345; AKhalifman@hotmail.com

#include <iostream> using namespace std; class MyClass { public: MyClass(int nRows, int nCols); int getArray(int iRow, int iCol); void setArray(int iRow, int iCol, int iVal); private: void initArray(); int **m_array; int m_Rows; int m_Cols; }; MyClass::MyClass(int nRows, int nCols) { m_Rows = nRows; m_Cols = nCols; initArray(); } void MyClass::initArray() { // dynamic allocation of 2-D arrays int iRow; m_array = (int **) malloc(m_Rows *sizeof(int)); for(iRow=0;iRow < m_Rows;iRow++) m_array[iRow] = (int *) malloc(m_Cols*sizeof(int)); } int MyClass::getArray(int iRow, int iCol) { if (iRow>0 && iRow<m_Rows && iCol>0 && iCol<m_Cols) return m_array[iRow][iCol]; else return 0; } void MyClass::setArray(int iRow, int iCol, int iVal) { if (iRow>0 && iRow<m_Rows && iCol>0 && iCol<m_Cols) m_array[iRow][iCol] = iVal; } int main() { int nRows = 120; int nCols = 30; class MyClass A(nRows, nCols); int result; A.setArray(30, 20, 123); result = A.getArray(30,20); cout << result << endl; A.setArray(nRows-1, nCols-1, 368); result = A.getArray(nRows-1, nCols-1); cout << result << endl; return 0; }

This code may be helpful for 2d array dynamic initialization in C++ int **a; int rows=3,cols=4;//3X4 matrix a=new int* [rows]; for(int i=0;i<rows;i++) *(a+i)=new int[cols]; Happy Coding Shantanu Happy Coding Shantanu

This code may be helpful for 2d array dynamic initialization in C++ int **a; int rows=3,cols=4;//3X4 matrix a=new int* [rows]; for(int i=0;i<rows;i++) *(a+i)=new int[cols]; Happy Coding Shantanu