Reading a text file using stdin then traversing through multiple arrays

I got a text file that is a single line of a string. For example:

Quote:

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I’m John

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I need to read the file using stdin then traverse each characters into multiple arrays where each row shifts to the left by one character:

Quote:

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row1 = [I, ‘ , m , , J , o , h , n]
row2 = [‘ , m , , J, o , h, n , I ]
row3 = [m , , J , o , h, n, I , ‘ ]
row4 = [, , J , o , h , n , I , ‘ , m]
...
rown = [n , I , ‘ , m , , J , o , h ]

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It is important to note the length of the arrays and number of arrays I create are variable that are dependent on the length of the string from the text file (n*n). In this case it would be 8*8 characters, so I need to create 8 arrays with 8 length each. Any help please?

Code:

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#include <iostream>
#include <string>
 
inline char get_char_at(const std::string& s, int row, int col) {
    return s[(row + col) % s.size()];
}
 
int main() {
    std::string s;
    for (char ch; std::cin >> ch; )
        s.push_back(ch);


    for (int row = 0; row < int(s.size()); ++row) {
        for (int col = 0; col < int(s.size()); ++col)
            std::cout << get_char_at(s, row, col) << ' ';
        std::cout << '\n';
    }
}

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