В коде не работает команда length_of_text и strtok, в чем может быть проблема?

#include <iostream>
#include <string>
using namespace std;
int main()
{
    const char znak[12] = { " ,:;./!?-_\n" };
    char* input = new char[200];
    cout << "Enter the text(max 200 characters)\n";
    cin.getline(input, length_of_text);
    system("cls");
    std::cout << "Words beginning and ending with a digit: " << std::endl;
    char* text = strtok(input, znak);
    while (text != NULL)
    {
        if (isdigit(text[0]) && isdigit(text[strlen(text - 1)]))
            std::cout << text << ", ";
        text = strtok(NULL, znak);
    }
    delete[] input;
    getchar();
    return 0;
}

#include <iostream>
#include <string>
#include <windows.h>
 
using namespace std;
int main()
{
    const char znak[12] = { " ,:;./!?-_\n" };
    char* input = new char[200];
    int length_of_text = 0;
    cout << "Enter the text(max 200 characters)\n";
    cin.getline(input, length_of_text);
    system("cls");
    std::cout << "Words beginning and ending with a digit: " << std::endl;
    char* text = strtok(input, znak);
    while (text != NULL)
    {
        if (isdigit(text[0]) && isdigit(text[strlen(text - 1)]))
            std::cout << text << ", ";
        text = strtok(NULL, znak);
    }
 
    delete[] input;
    system("PAUSE");
 
    return 0;
}

#include <iostream>
#include <string>
using namespace std;
 
int main()
{
    char* input = new char[200];
    cout << "Enter the text(max 200 characters)\n";
    cin.getline(input, 200);
    system("cls");
    cout << "Words beginning and ending with a digit: " << endl;
 
    const char* znak = " ,:;./!?-_\n";
    char* text, * next_text;
    int i = 0;
    text = strtok_s(input, znak, &next_text);
    while (text)
    {
        if (isdigit(text[0]) && isdigit(text[strlen(text) - 1]))
            cout << text << ", ";
        text = strtok_s(NULL, znak, &next_text);
    }
    delete[] input;
    getchar();
    return 0;
}

#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <string>
using namespace std;
int main()
{
    const char znak[12] = { " ,:;./!?-_\n" };
    char* input = new char[200];
    cout << "Enter the text(max 200 characters)\n";
    cin.getline(input, 200);
    system("cls");
    std::cout << "Words beginning and ending with a digit: " << std::endl;
    char* text = strtok(input, znak);
    while (text != NULL)
    {
        if (isdigit(text[0]) && isdigit(text[strlen(text) - 1]))
            std::cout << text << ", ";
        text = strtok(NULL, znak);
    }
    delete[] input;
    getchar();
    return 0;
}