CODEWITHSUNDEEP
c++arrayspointersmultidimensional-array
adfgvx
adfgvx

Reputation: 45

How to add chars to 2D array?

My code:

FILE * file;

file = fopen("c://catalog//file.txt", "r");
int m,n; //size of 2d array (m x n)
fscanf(file, "%d", &m);
fscanf(file, "%d", &n);
fclose(file);

printf("Size: %d x %d\n", m, n);

// create 2d array 
char **TAB2 = new char*[m];
for (int i = 0; i < m; i++)
    char *TAB2 = new char[n];

// display 2d array 
for (int i = 0; i < m; i++){
    for (int j = 0; j < n; j++)
    {
        printf("%c ", &TAB2[i][j]);
    }
    printf("\n");
}

How fill this array with chars or string? for example text = "someting", and for array 3x5 will be:

S o m e t
h i n g ?
? ? ? ? ?

I tried: TAB2[0][0] = 's'; *&TAB2[0][0] = 's'; for one char, and this does'nt work...

Probably I badly use pointers(?). Anyone help me?

Upvotes: 1

Views: 2065

Answers (2)

gsamaras
gsamaras

Reputation: 73366

The dynamic allocation array is wrong.

char **TAB2 = new char*[m];
for (int i = 0; i < m; ++i)
    TAB2[i] = new char[n];

Check this link for help.

You could try this:

#include<iostream>
using namespace std;

int main() {

  const int m = 3, n = 5;
  char **TAB2 = new char*[m];
  for (int i = 0; i < m; ++i)
      TAB2[i] = new char[n];

  char c;
  for (int i = 0; i < m; ++i) {
    for (int j = 0; j < n; ++j) {
      std::cin >> c;
      TAB2[i][j] = c;
    }
  }

  for (int i = 0; i < m; ++i) {
    for (int j = 0; j < n; ++j) {
      std::cout << TAB2[i][j];
    }
    std::cout << "\n";
  }

  // NEVER FORGET TO FREE YOUR DYNAMIC MEMORY
  for(int i = 0; i < m; ++i)
    delete [] TAB2[i];
  delete [] TAB2;

  return 0;
}

Output:

jorje
georg
klouv
jorje
georg
klouv

Important links:

  1. How do I declare a 2d array in C++ using new?
  2. How do I use arrays in C++?

Upvotes: 2

Codor
Codor

Reputation: 17605

The allocation of the array seems incorrect; it should be as follows.

char **TAB2 = new char*[m];
for (int i = 0; i < m; i++)
    TAB2[i] = new char[n];

Upvotes: 2

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