Copy an array of char into a multidimensional array of char

[scaar]

I have a set of hard coded arrays of char and I want to use them in order to fill a multidimensional array of char.
Unfortunately I cannot use std::string.

I have written something like that:

class Node
{
  char name[10][64];

  Node()
  {
     sprintf_s(name[0][0], "name1");
     sprintf_s(name[1][0], "name2");
     sprintf_s(name[2][0], "name2");
     ......
  }
}

That solution doesn't work and I have an compile time error:
Couldn't match type 'char(&)[_Size]' against 'char'

but I don't understand the problem.

I also tried a different solution:
memcpy(&name[0][0], "name1", sizeof(name[10][60]))

but again this doesn't work.

What I'm doing wrong.
If it's possible I would avoid a solution with a cycle, is it possible?

[MikeyBoy]

name[0][0] isn't a string, it's a single character.

name[0] is the string you want to fill.

[JRManx]

First of all, what is sprintf_s()? I have never seen that before, and it's not in any library that I have. When I wrote a short program to test the 2D array, I got errors telling me that "sprintf_s is an undeclared identifier."

If you're using a special non-standard library, you want to be careful because that can cause portability issues. Meaning your program will crash on someone else's computer. If it was just a mistake, then disregard my rant.

Moving on, your next problem is that you're trying to fill a single char variable name[0][0] with an entire string. So, you're basically trying to put a whole word into a space that's only big enough to hold a letter. That's not going to work.

Here's a simple program that demonstrates a 2-dimensional C string like the one you're trying to implement.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

#include <cstdio> // needed for puts() and sprintf() int main () { char name[10][64]; // using name[0], which is a 1-dimensional array // instead of name[0][0], which is a single char sprintf (name[0], "name1"); sprintf (name[1], "name2"); sprintf (name[2], "name3"); // using puts() here because it's simpler than std::cout puts (name[0]); puts (name[1]); puts (name[2]); return 0; }

$ c++ -std=c++2a -Wall -Wextra -pedantic untitled.cc -o a.out $ ./a.out name1 name2 name3 $

Why can't you use std::strings? They're much easier and more convenient to work with. Is this a homework assignment or something like that, that wants you to learn about C-strings?

But anyway, hope this helps!
max

[jonnin]

_s is microsoft trying to stick their oar in again. Its supposedly more secure than the normal one.

[JRManx]

Ah. Aside from the portability issue, if Microsoft says their version of something is "more secure," then I immediately distrust it.

I have had enough problems with their computers that I have a deeply-rooted distrust for anything labeled with the Windows logo. And no, it's not just me.

[seeplus]

The MS -s versions take an extra size parameter. However, if using C++ there are overloaded versions that automatically obtain the size by using the standard template technique to obtain array size.

[JRManx]

The MS -s versions take an extra size parameter.

That sounds like snprintf().

[seeplus]

Yes - except that for MS C++ the size parameter for sprintf_s can be omitted but can't be for snprintf(). There's also a difference re buffer overflow.

I prefer snprintf()

[George P]

what is sprintf_s()?

Something from the C11 standard.
https://en.cppreference.com/w/c/io

MS may have introduced the concept, but the standard committee decided it was something worthy a decade ago. Better error handling.

This is a good example of how the C libraries in the C++ standard are deviating from the C standard.

[JRManx]

Ah! Well, that explains why it wouldn't compile as C++...I think?

[mbozzi]

sprintf_s is part of Annex K, so you have to
#define __STDC_WANT_LIB_EXT1__ 1
before you
#include <stdio.h>
Then you can use it, if it is implemented (it's optional).

http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2310.pdf

[scaar]

Yes, this is an exercise and that's why I cannot use strings and I have to use arrays of char.

Then yes, I'm studing under Windows, using visual studio code with MS visual studio c++.

Thanks to all for the answers.