My Java Program is below. It's my training exercise. The one implements stack stucture for special type of string parsing(string with delimiter).
This delimiter-matching program works by reading characters from the string one at a time and placing opening delimiters when it finds them, on a stack. When it reads a closing delimiter from the input, it pops the opening delimiter from the top of the stack and attempts to match it with the closing delimiter. If they’re not the same type (there’s an opening brace but a closing parenthesis, for example), an error occurs. Also, if there is no opening delimiter on the stack to match a closing one, or if a delimiter has not been matched, an error occurs. A delimiter that hasn’t been matched is discovered because it remains on the stack after all the characters in the string have been read.
I use Eclipse. My output is here:
Please enter String:
{}
ch0 = {
ch1 = }
chLabel1 = **UNDEFINED CHAR(SQUARE WITH QUESTION MARK INSIDE IT)**
Error at }**
Could you explain value of chLabel?
As I understand operator "|" (here, cause two operands have boolean type) - is "lazy", shortcut version of "||" operator. I've tested the program after substitution "|" for "||"-result is the same.
public class MyStack {
private int top=0;
private int maxSize=0;
private char[] charArray=null;
public MyStack(int size){
maxSize=size;
top=0;
charArray=new char[maxSize];
}
public void push(char ch){
charArray[top++]=ch;
}
public char pop(){
return charArray[top--];
}
public boolean isEmpty(){
if(top==0)
return true;
else return false;
}
public boolean isFull(){
if(top==(maxSize-1))
return true;
else return false;
}
}
class StringParse {
private String stringForParsing = null;
public StringParse(String string) {
this.stringForParsing = string;
}
public void parser() {
char[] chArr = stringForParsing.toCharArray();
MyStack mySt = new MyStack(chArr.length);
for (int i = 0; i < chArr.length; i++) {
char ch = chArr[i];
switch (ch) {
case '{':
case '(':
case '[':
mySt.push(ch);
System.out.println("ch" + i + " = " + ch);
break;
case '}':
case ')':
case ']':
if (mySt.isEmpty())
System.out.println("Error at" + ch);
else {
char chLabel = mySt.pop();
System.out.println("ch" + i + " = " + ch);
System.out.println("chLabel" + i + " = " + chLabel);
if ((chLabel == '{') && (ch == '}') | (chLabel == '(') && (ch == ')') | (chLabel == '[') && (ch == ']'))
break;
else {
System.out.println("Error at " + ch);
break;
} // end of second else
} //end of first else
default:
break;
} //end of switch
} //end of parser method
}
} //end of class
class Main {
public static void main(String[] args) throws IOException {
BufferedReader br = new BufferedReader(new InputStreamReader(System. in ));
System.out.println("Please enter String:");
String s = br.readLine();
StringParse strP = new StringParse(s);
strP.parser();
}
}
