Replacing multidimensional array with another one?

Question

I'm making an 2D Game to train my class managment.

I have two multidimensional arrays: Map1 and Map. I want to replace Map values with Map1 ones. How can I do this without replacing every element manually like Map[0][0] = '#' etc.

char Map[10][21] = {
    "####################",
    "#                  #",
    "#                  #",
    "#                  #",
    "#                  #",
    "#                  #",
    "#                  #",
    "#                  #",
    "#                  #",
    "####################"};

char Map1[10][21] = {
"####################",
"#                  #",
"#                  #",
"#                  #",
"#                  #",
"#       TEST       #",
"#                  #",
"#                  #",
"#                  #",
"####################"};

A.S.H · Accepted Answer · 2016-12-26 16:30:46Z

1

Since multi-dimensional arrays are guaranteed to be contiguous in memory layout, and the two arrays have the same size, you can do this:

std::copy((char*)Map1, (char*)Map1 + sizeof(Map1), (char*)Map);

Note that the cast is necessary to make the whole copy as a array of char.

On the other hand, this task would have been more straightforward if you used std::vector<std::string>, you could directly assign: Map = Map1...

edited Dec 26, 2016 at 16:30

answered Dec 26, 2016 at 16:02

A.S.H

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Comments

lakeweb · Accepted Answer · 2016-12-26 15:56:27Z

0

I personally would not write code like this, but for testing...

int main( )
{
    for( size_t i= 0; i < 10; ++i )
        std::cout << Map[ i ] << std::endl;

    memcpy( Map, Map1, sizeof( Map ) );

    for( size_t i= 0; i < 10; ++i )
        std::cout << Map[ i ] << std::endl;
}

answered Dec 26, 2016 at 15:56

lakeweb

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Comments

Dietmar Kühl · Accepted Answer · 2016-12-26 16:01:02Z

0

Just leverage the built-in copy assignment for classes:

struct map {
    char Map[10][21];
};

map Map = { 
    "####################",
    "#                  #",
    "#                  #",
    "#                  #",
    "#                  #",
    "#                  #",
    "#                  #",
    "#                  #",
    "#                  #",
    "####################"
};

map Map1 = {
    "####################",
    "#                  #",
    "#                  #",
    "#                  #",
    "#                  #",
    "#       TEST       #",
    "#                  #",
    "#                  #",
    "#                  #",
    "####################"
};

int main()
{
    Map = Map1;
}

answered Dec 26, 2016 at 16:01

Dietmar Kühl

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Comments

Rama · Accepted Answer · 2016-12-26 16:30:57Z

0

Instead of copying them, maybe it is more successful to exchange its contents, this can be done using std::swap

swap(Map,Map1);

answered Dec 26, 2016 at 16:30

Rama

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