How to strcat with intervals in C++?

Question

So here's my code:

#include <iostream>
#include <string.h>
using namespace std;

const int MAX_SIZE1 = 20;
const int MAX_SIZE2 = 10;

int main()
{
    char a[MAX_SIZE1][MAX_SIZE1][MAX_SIZE2];
    int n, i, j;
    cin >> n;
    for (i = 0; i < n; i++)
        for (j = 0; j < n; j++)
            cin >> a[i][j];

    char s[MAX_SIZE1 * MAX_SIZE1 * (MAX_SIZE2 - 1) + 1];
    int hor = 0, vert = 0;
    while (hor < n / 2 && vert < n / 2)
    {
        for (i = vert; i < n - vert; i++)
            strcat(s, a[hor][i]);
        for (i = hor + 1; i < n - hor; i++)
            strcat(s, a[i][n - vert - 1]);
        for (i = n - vert - 2; i >= vert; i--)
            strcat(s, a[n - hor - 1][i]);
        for (i = n - hor - 2; i > hor; i--)
            strcat(s, a[i][vert]);
        hor++;
        vert++;
    }
    if (n % 2)
        for (i = vert; i < n - vert; i++)
            strcat(s, a[hor][i]);
    else
        for (i = hor; i < n - hor; i++)
            strcat(s, a[i][vert]);
    cout << s << endl;
    return 0;
}

I've got some questions. How to modify it in order to get intervals between the words in the outputted s string? And how to get rid of the awkward 50 rows (literally) long weird symbols in the beginning of my output?

EDIT: I'm sorry. Thought it didn't matter. The input should be a maximum of 20x20 array of words which do not exceed 9 characters each. The output should be an s string which represents a sentence formed by reading the array in a clockwise spiral beginning from the top left corner. Problem is.. I got weird symbols in the beginning of my output and get no intervals between the words.

Please provide specific input and expected output. We cannot type 20x20x10 times in order to test your program. — herohuyongtao, Jan 23 '14 at 17:42
In C++, you'd use `std::string` rather than this C-style gibberish. — Mike Seymour, Jan 23 '14 at 17:42

score 3 · Accepted Answer · answered Jan 23 '14 at 18:13

Use C++ instead of C

Since you are using C++, you should really write your code in a C++ way, using std::string. One of your problems (uninitialized string) can be fixed this way, since it is impossible to define an uninitialized string in C++.

Replace

#include <string.h>

by

#include <string>

Replace

char s[MAX_SIZE1 * MAX_SIZE1 * (MAX_SIZE2 - 1) + 1];

By

std::string s;

Replace

strcat(s, a[hor][i]);

by

s = s + a[hor][i];

If you still want to use C

You have to initialize your output string:

char s[MAX_SIZE1 * MAX_SIZE1 * (MAX_SIZE2 - 1) + 1] = "";

Uninitialized strings typically contain rubbish, and strcat adds to it, rather than removing it.

In addition, if you want delimiters, you should code that explicitly; strcat doesn't add any delimiters itself:

strcat(s, ",");

Thanks a lot ! I have another question. Would really appreciate it if you would answer or at least give me a hint. Reading the array clockwise starting from the top left corner was relatively easy but I can't seem to figure how to do it anticlockwise and starting from the bottom right corner. — user3213110, Jan 23 '14 at 19:26
@user3213110 Please post this as a separate question, in order to prevent confusion — anatolyg, Jan 23 '14 at 19:28

How to strcat with intervals in C++?

1 Answers1

Use C++ instead of C

If you still want to use C