Copy a matrix/2d array to another in c++

Question

I am trying to copy a 2d array into another 2d array, i have these two array created:

#define mapXcor 50
#define mapYcor 50

char secondStage    [mapXcor][mapYcor];
char currentStage   [mapXcor][mapYcor];
//mapXcor and mapYcor are constant integers

Now my secondStage[][] array is populated with values on it, but currentStage[][] isn't, and i want to assign the values of secondStage to currentStage. So i created the function bellow:

void populateArray(char (&arrayA)[mapXcor][mapYcor], char arrayB[mapXcor][mapYcor]) {
    for(int a = 0; a < mapXcor + 1; ++a) {
        for(int b = 0; b < mapYcor + 1; ++b) {
            arrayA[mapXcor][mapYcor] = arrayB[mapXcor][mapYcor];
        }
    }
}

populateArray(currentStage[mapXcor][mapYcor],secondStage[mapXcor][mapYcor]);

But when i use the function it gives me a error :

1 IntelliSense: a reference of type "char (&)[20][50]" (not const-qualified) cannot be initialized with a value of type "char"

2 IntelliSense: argument of type "char" is incompatible with parameter of type "char (*)[50]"

How could I fix this?

Solution 1

change the assignment sentence in your for-loop:

arrayA[mapXcor][mapYcor] = arrayB[mapXcor][mapYcor];

by

arrayA[a][b] = arrayB[a][b];

Solution 2

Code you probably are trying to reach. Do not show it to teacher :-) - there is too much from practical programming. Just look and then write your own solutions:

#include <string.h>
#include <stdio.h>

#define mapXcor 5
#define mapYcor 5

static char secondStage    [mapXcor][mapYcor];
static char currentStage   [mapXcor][mapYcor];

void populateArray(char (&arrayA)[mapXcor][mapYcor], const char (&arrayB)[mapXcor][mapYcor]) {
/*
    for(int a = 0; a < mapXcor; ++a) {
        for(int b = 0; b < mapYcor; ++b) {
            arrayA[a][b] = arrayB[a][b];
        }
    }
*/
    memcpy(arrayA, arrayB, sizeof(arrayB));
}

int main()
{
    for(int a = 0; a < mapXcor; ++a) {
        for(int b = 0; b < mapYcor; ++b){
            currentStage[a][b] = a*b + 10*a;
        }
    }

    populateArray(secondStage, currentStage);

    for(int a = 0; a < mapXcor; ++a) {
        for(int b = 0; b < mapYcor; ++b){
            printf("%2i ", secondStage[a][b]);
        }
        printf("\n");
    }

    return 0;
}

Comments:

• You have bad array index limits in cycle. Look for corrected function under comment.
• You have wrong indexes in assignment in cycle. Again, commented out code.
• If you passed one array by reference (destination) why not to use constant reference for source?
• In practice as your areas have the same type (you could even define them as having the same type) nobody copies them by elements. I have used memcpy() but this is only good if memory areas do not overlap (in this case - yes). check man 3 memcpy.
• Learn harder :-)