No matching function for call to class constructor?

I am currently working on assignment for one of my classes.
I am trying to construct a class, but when I try to run the program I get this error:

no matching function for call to 'Word::Word()

here is the code that I created:

#include <iostream>
//#include <iomanip>
//#include <string>
//#include <cctype>
//#include <cmath>
//#include <fstream>
//#include <vector>
//#include <algorithm>

using namespace std;

string wordToTest;

class Word{
    public: 
        int length;
        string word;
        void TestForPalindrome();
        Word(string w){
            word = w;
            length = word.length();
        }
};

void Word::TestForPalindrome(){
    string testWord;
    for(int i = length; i < 0; i--){
        testWord += word[i];
    }
    if (testWord == word){
        cout << word << " is a palindrome!";
    } else if (testWord != word){
        cout << word << " is not a palindrome";
    }
}

//error occurs here
void GetInput(){
    cout << "enter a word: \n";
    cin >> wordToTest;
    Word Palindrome(wordToTest);
    Palindrome.TestForPalindrome();
}



int main(){
    
    return(0);
}

the error occurs at the comment.
Thanks in advance for any help on this!

>Solution :

Because you only define one constructor that requires a string, so you must initialise Palindrome with a string. So you can use a temporary string to receive the input. By the way, global variable is not recommanded.

Here the update GetInput():

void GetInput(){
    string tmp; // Use a temporary string to receive.
    cout << "enter a word: \n";
    cin >> tmp;
    Word Palindrome(tmp); // Initialise with the temporary string.
    std::cout << Palindrome.word << std::endl;
    Palindrome.TestForPalindrome();
}

I also find another issue with your code: in the function TestForPalindrome():

for(int i = length; i < 0; i--){
        testWord += word[i];
    }

You want to create a reversed string of word, however, since length is greater or equal than 0, and the condition of loop is i < 0, so code in this loop will never be executed.

Here is an update of the loop:

for (int i = length - 1; i >= 0; i--) {
        testWord += word[i];
    }