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digitalmars.D.learn - double[][] to double**

reply "Danny Arends" <Danny.Arends gmail.com> writes:
I need to call some C code which takes a double**

In D I have a dynamic array X, Whats a good way of doing this ?

#SNIP

extern(C){
   void toCall(double** X, size_t d1, size_t d2);
}

void main(){
   double[][] X;

   // How to be able to:
   toCall(X, X.length, X[0].length);
}

#/SNIP

Danny Arends
http://www.dannyarends.nl
Feb 10 2013
parent reply =?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:
On 02/10/2013 11:38 AM, Danny Arends wrote:
 I need to call some C code which takes a double**

 In D I have a dynamic array X, Whats a good way of doing this ?

 #SNIP

 extern(C){
 void toCall(double** X, size_t d1, size_t d2);
 }

 void main(){
 double[][] X;

 // How to be able to:
 toCall(X, X.length, X[0].length);
 }

 #/SNIP

 Danny Arends
 http://www.dannyarends.nl
You need to use two properties of slices: .ptr: Pointer to the first element .length: The number of elements import std.stdio; import std.algorithm; import std.range; extern(C) { void toCall(double** X, size_t d1, size_t d2) { for (size_t row = 0; row != d1; ++row) { for (size_t column = 0; column != d2; ++column) { writefln("%s,%s: %s", row, column, X[row][column]); } } } } void main(){ double[][] X = [ [ 1, 2, 3 ], [ 10, 20, 30 ] ]; double*[] X_c = X.map!(d => d.ptr).array; toCall(X_c.ptr, X_c.length, X[0].length); } The line with map is the equivalent of the following: double*[] X_c; foreach (slice; X) { X_c ~= slice.ptr; } Ali
Feb 10 2013
parent reply "Danny Arends" <Danny.Arends gmail.com> writes:
Thanks so much !

Why is this not easy 2 find :P
Feb 10 2013
parent =?UTF-8?B?QWxpIMOHZWhyZWxp?= <acehreli yahoo.com> writes:
On 02/10/2013 12:05 PM, Danny Arends wrote:
 Thanks so much !

 Why is this not easy 2 find :P
We all know the feeling. :) For future reference: The spec: http://dlang.org/arrays.html#array-properties TDPL: 4.6 Arrays' Maverick Cousin: The Pointer Programming in D: http://ddili.org/ders/d.en/pointers.html ("The .ptr property of arrays" section.) Ali -- D Programming Language Tutorial: http://ddili.org/ders/d.en/index.html
Feb 10 2013