C ++ error I keep getting this error variable-sized object `OldWord' may not be initialized

#include<iostream>
#include<cctype> 
#include<string>
#include<cstdlib>
#include"Palindrome.h"
using namespace std;

int main()
{
        Stack S1;
        string word;

        cout << "Do you know what a Palindrome is?\n";
        cout << "It is a word that is the same spelling backwards and forward\n";

开发者_StackOverflow中文版        cout << "Enter in a word";
        cin  >> word;

        char OldWord[word.length] = word;
                cout << OldWord[2];
        return 0;
}

If I put 20 in place of word.length, I get "invalid initializer" for error

Well, arrays are neither copyable nor assignable; you have to copy them in a loop, element by element (or use a function that does that for you). In addition, the length of a local array variable must be a compile-time constant; you can't set it at runtime.

Also, std::string is not an array; why do you think that this assignment would work?

std::string does allow array-like access, though, so you can use word[2], assuming there are at least three characters in the string. In general, raw arrays should be avoided in C++; there are much better options, like std::string, std::vector, and std::array (or std::tr1::array or boost::array).

Leave it with 20 instead of word.length and use strcpy to initialize.

The value needs to be copied into OldWord.

Try changing:

char OldWord[word.length] = word;

to

char OldWord[20]; // you mentioned 20...
strcpy(OldWord, word.c_str());