expected primary-expression before ‘)’ token error on a while loop in a function

My issue is that I keep getting the "expected primary-expression before ')' token" error on the variable "string" in the while loop in the NumWords function. The variable works fine in the "istringstream inSS(string);" line but when I try to compile the code the next line produces that error. Please help I am so confused and it is driving me crazy.

#include <iostream>
#include <sstream>
#include <string>
using namespace std;

//Function prototypes

int NumWords(const string&);

int NumNonWSCharacters(const string&);

void CharReplace(string&, char, char);

char PrintMenu();

//Main function

int main () {

//Variables
string text;

//Input & Output original
cout << "Enter a line of text: ";
getline(cin, text);
cout << "\n";
cout << "You entered: " << text << "\n";

//How many words
cout << NumWords(text);

}

//Counts the number of words in a string

int NumWords(const string&) {
int count = 0;
istringstream inSS(string);
while (inSS >> string) {

    count++;

}


}

//Count the number of characters (not including whitespace) in a string

int NumNonWSCharacters(const string&) {

    cout << "FINISH\n";

}

//Replaces one character with another in a given string

void CharReplace(string&, char, char) {

    cout << "FINISH\n";

}

//Prints the menu

char PrintMenu() {

    cout << "FINISH\n";

}