Ошибка Run-Time Check Failure #2 - Stack around the variable 'str' was corrupted

#include "pch.h"
#include "string"
#include "conio.h"
#include "iostream"
#include "Windows.h"
#include <sstream>
using namespace std;
int main()
{
    setlocale(LC_ALL, "rus");
    SetConsoleCP(1251);
    SetConsoleOutputCP(1251);
    char str[80];
    cout << "Введитете строку > "; cin.get(str, 80);
    char word[1][7];
    int k = 0;
    for (int i = 0; i < strlen(str); i++)
    {
        while (str[i] == ' ')
            continue;
        int j = 0;
        while (str[i] != ' ' && str[i] != '\0')
            word[k][j++] = str[i++];
        word[k++][j] = '\0';
    }
    char *sh_word = new char[100];
    for (int i = 0; i < k; i++)
    {
        strcpy_s(sh_word, sizeof(100),word[i]);
        int num = i;
        for (int j = i; j < k; j++)
            if (strlen(word[j]) < strlen(sh_word))
            {
                strcpy_s(sh_word, sizeof(100), word[j]);
                num = j;
            }
        strcpy_s(word[num], sizeof(100),word[i]);
        strcpy_s(word[i], sizeof(100),sh_word);
    }
    for (int i = 0; i < 4; i++)
        cout << word[i] << ", ";
    memset(str, 0, sizeof(str) / sizeof(str[0]));
    memset(word, 0, sizeof(word) / sizeof(word[0]));
    system("pause");
    return 0;
}