1217 experimental four recursive descent grammar analysis program design

Import Java.util.Scanner;

public class Dealmain {

Public Dealmain () {
TODO Auto-generated constructor stub
String Allchar = new string ();
Scanner input=new Scanner (system.in);//define keyboard to receive data
System.out.print ("Please enter:");
Allchar = Input.next ();
Char[] P =allchar.tochararray ();
for (int i = 0; i < p.length-1; i++) {
char C = p[i];
if (c== '/' | | c== ' * ' | | c== ' + ' | | c== '-' | | c== ' = ')) {
if (p[i+1]== '/' | | p[i+1]== ' * ' | | p[i+1]== ' + ' | | p[i+1]== '-' | | p[i+1]== ' = ') {
SYSTEM.OUT.PRINTLN ("Symbol syntax error");
System.exit (0);
}else if (i==0&&c!= '-') {
SYSTEM.OUT.PRINTLN ("Symbol syntax error");
System.exit (0);
}
}
if (48<=c&&c<=57) {
if ((p[i+1]>=65&&p[i+1]<=90) | | | (p[i+1]>=97&&p[i+1]<=122)) {
SYSTEM.OUT.PRINTLN ("Variable syntax error");
System.exit (0);
}
}
if ((p[i+1]>=65&&p[i+1]<=90) | | | (p[i+1]>=97&&p[i+1]<=122)) {
if (48<=c&&c<=57) {
SYSTEM.OUT.PRINTLN ("Variable syntax error");
System.exit (0);
}
}
}
System.out.println ("is the correct expression");
}
public static void Main (string[] args) {
New Dealmain ();

}

}

1217 experimental four recursive descent grammar analysis program design