string laborotary project

#include<iostream>
#include<string>
#include<stdio.h>
using namespace std;
int main()
{
    int i = 5;
    char* str= new char[i];
    bool flag;
    cout << "Enter elements of your string:" << endl;
    do
    {
    cin >> str[i];
    if (str[i] = 1, 2, 3, 4, 5, 6, 7, 8, 9, 0)
    {
        flag = true;
    }
    }
    while (flag==false);
    int j = strlen(str);
    cout << "Lenght of your string :" << j << endl;
    delete[] str;
}