kinda new need help

Hey there im taking a intro course to c++ and we have a small assignment where we have the user input a string like:
He was 14 ten years ago. The next line should display just the numbers.
14.

Code:

int main()
{

	char word[20];
	int a;
	cout<<"Enter a sentence with at least one number in it."<<endl;
	cin.getline(word,20);
	for(word[20])
	{
	if(!isdigit((unsigned char)word[20])>=0)
	{
	cout<<word<<endl;
	}
	}
	system("PAUSE");

}

i also know i have all the appropriate includes just need to know how to get the isdigit to check the string and pull the numbers for display.
thanks ahead of time.

What? You are not making any sense as to what you want to do.
Also, it is a good idea to replace char word[20] with std::string word and cin.getline(...) with std::getline(std::cin, word).