Here is a simple example of checking that a given equation has correctly matched parenthesis. It could be expanded to multiple types of parenthesis, but this version simply shows for ( ) type.

Examples:

• ()), ((), ()(())) would not be accepted
• (((()))), ()()(()()), ()(())() would be

public boolean check_parenthesis(char equation[])
{
	int i, unmatched=0;
	for(i=0; i < equation.length; i++)
	{
		if(equation[i]==')')
		{
			unmatched--;
			if(unmatched < 0)
				return false;
		}
		else if(equation[i]=='(')
		{
			unmatched++;
		}
	}
	return (unmatched==0);
}