Multi dimensions array pointer population

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hello everybody. hope you are safe.
i am trying to write such a code:

char * ARR = new char[3][3];
ARR[3][3]={92,124,47,196,254,196,47,124,92};

but it returns error.
the number inside are not integer as they look; they are character ascii code.
even using a new pointer with more than 1 dimension it messes up.
what syntax should i use?
thanks

What I have tried:

just usin 1 dimension a time
however is not i m looking for.
populate multiple dimension in one line save me coding.

Posted 29-Nov-20 7:42am

Mat 257

Updated 29-Nov-20 23:10pm

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Rick York · Answer 1 · 2020-11-29T08:21:00

Why allocate that? It can live on the stack if you want it to because it is nine bytes. This :

C++

const char arr[3][3] =
{
      {  92, 124,  47 }
    , { 196, 254, 196 }
    , {  47, 124,  92 }
};

will work.

If you really have to allocate it, you might find it easier understand if you define a type for it.

C++

const int SmallArraySize = 3;
typedef char smallArray[ SmallArraySize ];

const int LargeArraySize = 3;
smallArray * arr = new smallArray[ LargeArraySize ];

and you can still access it as arr[x][y].

OriginalGriff · Answer 2 · 2020-11-29T08:25:00

Solution 2

Try:

C++

char ARR[3][3] = {{92,124,47},{196,254,196},{47,124,92}};

Posted 29-Nov-20 8:25am

OriginalGriff

CPallini · Answer 3 · 2020-11-29T20:24:00

As others already pointed out, you don't need to dynamically allocate memory, you might use the stack, instead.
With C++ you have more options, you could, for instance, use a std::vector or a std::array.
Try

C++

#include <iostream>
#include <vector>
#include <array>
using namespace std;

int main()
{
  // using a vector
  vector < vector < unsigned char > > v{{92, 124, 47}, {196, 254, 196}, {47,124,92}};
  cout << static_cast<unsigned>(v[1][2]) << endl;

  // using an array
  array< array< unsigned char , 3 >, 3> a{{{{92, 124, 47}}, {{196, 254, 196}}, {{47,124,92}}}};
  cout << static_cast<unsigned>(a[1][2]) << endl;
}

k5054 · Answer 4 · 2020-11-29T09:40:00

If you absolutely need to allocate the array on the stack you can do the following

C++

char (*ARR)[3] = new( char [5][3] { { 192, 124, 47 },
                                     {196, 254, 196},
                                     {47, 124, 92},
                                     {154, 129, 197},
                                     {36, 49, 124} };

Note that we use char (*ARR)[3] to declare an pointer to array[3] of char. If we use char *ARR[3], we've declared an array[3] of pointer to char, and can't use the brace initialization.

Mat 257 · Answer 5 · 2020-11-29T23:10:00

Solution 5

thanks for this plenty of solutions.
i keep being surprised on how many variants this language has.
just moving a font along the string code can completely change how is ment to be and the code being executed. i wonder how can expert programmer hold in memory all these alternatives.

Posted 29-Nov-20 23:10pm

Mat 257

Multi dimensions array pointer population

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