Why does my program go into an infinite loop when someone enters an invalid input character?

#include<iostream>
using namespace std;
void mainMenu()
{
	int ch;
	cout<<"Main Menu"<<endl;
	cout<<"1. Customer"<<endl;
	cout<<"2. Item"<<endl;
	cout<<"3. Shopping"<<endl;
	cout<<"4. Quit"<<endl;
	cout<<"Choose one: "<<endl;
	cin>>ch;
	while( cin.fail() ) 
	{
cout << "Bad input, try again." << std::endl;
// Reset the stream.
cin.clear();
cin.ignore(std::numeric_limits<std::streamsize>::max(),''\n'');
cin>>ch;
	}
// until you enter integer value you will
//try to input new value

}