Copy elements of one array to another in C

Question

So I am trying to use char array in C to copy from one array to another, each element at a time, however, I am stuck at this part. I did try to research but may be I'm a dumb or what not, I still could not get it right. Here is my code:

Say I have two array

char arr1[1000][3]
char arr2[1000][3]

So wHat I mean is that [3] equal length of the string and each array has 1000 elements. So arr1[0] = "AB\0"

I can't, obviously, do arr1[i] = arr2[i]; won't work of course, I did try strcpy but don't quite get it right. Please help me out a bit, thank you :)

Here a portion of it, the specific function I writing: Please just answer the one I ask, I can do this easily in Java but I really learning C so... An example would be nice :D

//build stacks                                                                                                                                                                                                     
card_pos_ptr add_card(card_pos_ptr head, char card_list[1000][3], int index){
  int i,k = 0;
  int start_index = index;
  card_pos_ptr current = head;
  for(i=0;i<13;i++){
    for(k=0;k<4;k++){
      if(current->card_stack == NULL){
        card_ptr node = (card_ptr)malloc(sizeof(card));
    strcpy(node->card_name,);
        node->up = false;
        node->down = NULL;
        start_index++;
      }else{
        card_ptr node = (card_ptr)malloc(sizeof(card));
        //node->card_name[0] = card_list[start_index];                                                                                                                                                             
        node->up = false;
        node->down = current->card_stack;
        current->card_stack = node;
        start_index++;
      }
    }
    current = current->next_pos;
  }

}

Yeah, but it would be better to copy the entire array with a single call to memcpy, unless there's something preventing you from doing that. — Michael
– Michael, Commented Dec 4, 2013 at 9:18
Yes, I don't simply copy one array to another. What I am doing is copy content of each element in the big array and pass it in the small array in the struct. — Rozen
– Rozen, Commented Dec 4, 2013 at 9:20
The 1000x3 is genuine 2D, not to be confused with the pointer-array idiom most people call 2D. this one is actual 2D. The ones in the cards are 1D (obviously). Anyway, assuming each (both the 1000-card shoe and the nodes you're creating) are indeed made of 3-char arrays, there is no reason you can't memcpy() or strcpy() the data. Since you know they're all 2-char strings with a terminator, strcpy() is somewhat pointless. I'd memcpy() it over if I was told to do it this way. — WhozCraig
– WhozCraig, Commented Dec 4, 2013 at 9:37

Alex Johnson · Accepted Answer · 2019-08-21 14:43:58Z

4

Not sure what you are trying to do with this declaration but in frist place to declare array you need something like :

  char arr1[1000][3];
  char arr1[0][0] = 'A';
  char arr1[0][0] = 'B';
  ...

And in order to copy each element one at a time use a for loop:

if ( something that determines X ? ) {
    for ( int i=0; i < 3 ; i++ ) {
       arr2[x][i] = arr1[x][i];
    }
}

edited Aug 21, 2019 at 14:43

Alex Johnson

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answered Dec 4, 2013 at 9:15

Wald

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4 Comments

Rozen Over a year ago

No, each element in the char array contains more than 1 char, so it will be AB, not just A or B. Plus I tried assigning like ur example, the compiler say incompatible type assignment.

phuclv Over a year ago

1 dimensional is different from 2 dimensional array

Wald Over a year ago

Like I said i just wasn't sure what was he doing i answered before he edited his question. Does this help you ?

Rozen Over a year ago

This one would work fine too I guess, Beside the one answers under my question :) Thank you!

Cyborg-X1 · Accepted Answer · 2013-12-04 09:22:07Z

1

I would do it like this:

int i;
char arr1[1000][3];
char arr2[1000][3];

arr1[0][0]='v';

for(i=0;i<1000;++i)
{
    strncpy(arr2[i],arr1[i],3); //safe copy, copies max. 3 chars.
}

printf("%c\n",arr2[0][0]);

answered Dec 4, 2013 at 9:22

Cyborg-X1

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1 Comment

Rozen Over a year ago

appreciate your answer!

Srikanth · Accepted Answer · 2013-12-04 09:21:05Z

0

Try

memcpy( &node->card_name[0] ,card_list[start_index])

answered Dec 4, 2013 at 9:21

Srikanth

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1 Comment

Rozen Over a year ago

need 3 arguments for memcpy.

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