char *Data;
Data = new char[2, 10]; // This would create an array with 2 row and 10 chars per row
// do stuff
delete [] Data;
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Dynamic Multi Dimensional arrays
Author
I am busy with an app that requires multi dimensional arrays, However, since they differ per object I create them dynamicly. This is the source I tried:
Why doesn''t this work? I didn''t test it on a VC6 compiler but on Borland but that shouldn''t be the problem. I never tried this source at home but can anyone tell me what I might do wrong?
Sand Hawk
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Hi Sand_Hawk,
I don''t have a lot of experience with c++ but i think this is your solution:
#define length1 10
#define length2 2
char** data;
data = new char*[length1];
for (i = 0; i < length1; ++i)
data = new char[length2];
In c++, real multi dimensional arrays doesn''t exist. Instead you can use an array of array''s.
Glenn
I don''t have a lot of experience with c++ but i think this is your solution:
#define length1 10
#define length2 2
char** data;
data = new char*[length1];
for (i = 0; i < length1; ++i)
data = new char[length2];
In c++, real multi dimensional arrays doesn''t exist. Instead you can use an array of array''s.
Glenn
Author
Thanks for all the help so far. I''ve used this method:
I can write to the memory, but if I try to read it my programs crahes. I use Data[Y][X] to read 1 character.
Sand Hawk
----------------
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char** data;data = new char*[length1];for (i = 0; i < length1; ++i)data = new char[length2]; I can write to the memory, but if I try to read it my programs crahes. I use Data[Y][X] to read 1 character.
Sand Hawk
----------------
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Your method is correct, your problem must be in the size of the arrays or the value of x or y.
I must have posted this a million times over!
This should create aand delete a 3x3 array.
Peace out,
Mathematix.
Q3A + UT1999 = UT2003
therefore UT2003 - Q3A = UT1999
and UT2003 - UT1999 = Q3A!
[edited by - Mathematix on November 7, 2002 5:18:54 PM]
typedef float ARRAY[3]; // Just as an example.ARRAY *TwoDArray;TwoDArray = new ARRAY[3];// And to delete...delete [] TwoDArray; This should create aand delete a 3x3 array.
Peace out,
Mathematix.
Q3A + UT1999 = UT2003
therefore UT2003 - Q3A = UT1999
and UT2003 - UT1999 = Q3A!
[edited by - Mathematix on November 7, 2002 5:18:54 PM]
quote:Original post by Sand_Hawk
Thanks for all the help so far. I've used this method:char** data;data = new char*[length1];for (i = 0; i < length1; ++i)data = new char[length2];
I can write to the memory, but if I try to read it my programs crahes. I use Data[Y][X] to read 1 character.
Here's the problem. It should be:
char** data;data = new char*[length1];for (i = 0; i < length1; ++i)data[i] = new char[length2]; Note that each element in data is now getting a 1d array, making a 1d array of 1d arrays: ie a 2d array.
Mathematix's idea looks pretty neat, though.
Peace,
Doc
[edited by - doc on November 7, 2002 6:40:41 PM]
[edited by - doc on November 7, 2002 6:42:02 PM]
Author
I noticed I made a mistake in pasting the code. I used that code. However, coming back to the typedef, can I use a typedef to when I want to create dynamic X and Y axis because now you set it to max 3 on the rows.
Sand Hawk
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Sand Hawk
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Nope. That typedef will be fixed. Dynamic sized columns will have to be done the hard way.
Peace,
Brendon
Peace,
Brendon
Author
It seems like I am going crazy. I ran the debugger over it and it should work. Here is the code:
It is for the Ascii fishtank contest. What is wrong with the allocation code? And also, can I read the array from file the way I do it?
Sand Hawk
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int iIndex = 0; ifstream FishFile(FileName, ios::binary); // Load X and Y dimensions from the file FishFile.read((char *)&DimX, sizeof(int)); FishFile.read((char *)&DimY, sizeof(int)); // Allocate dynamic array with size of the fish FishData = new char*[DimY]; for (iIndex = 0; iIndex < DimY; iIndex++) FishData[iIndex] = new char[DimX]; // Read the fish from file FishFile.read((char *)FishData, sizeof(FishData)); It is for the Ascii fishtank contest. What is wrong with the allocation code? And also, can I read the array from file the way I do it?
Sand Hawk
----------------
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