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odev3_2.java
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odev3_2.java
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package odev3;
public class odev3_2 {
static int oncelik(char ch)
{
switch (ch) {
case '+':
case '-':
return 1;
case '*':
case '/':
return 2;
case '^':
return 3;
}
return -1;
}
static String terscevir(String exp){
String S="";
for (int i = exp.length()-1; i >=0; i--) {
switch (exp.charAt(i)) {
case '(':
S=S+")";
break;
case ')':
S=S+"(";
break;
default:
S=S+exp.charAt(i);
break;
}
}
return S;
}
static String infixToPrefix(String exp){
String S=terscevir(exp);
String donustur=infixToPostfix(S);
S=terscevir(donustur);
return S;
}
static String infixToPostfix(String exp)
{
String result = new String("");
Yigit stack= new Yigit(100);
for (int i = 0; i<exp.length(); ++i)
{
char c = exp.charAt(i);
if (Character.isLetterOrDigit(c))
result += c;
else if (c == '(')
stack.push(c);
else if (c == ')')
{
while (!stack.isEmpty() && stack.peek() != '(')
result += stack.pop();
if (!stack.isEmpty() && stack.peek() != '(')
return "Invalid Expression"; // invalid expression
else
stack.pop();
}
else // an operator is encountered
{
while (!stack.isEmpty() && oncelik(c) <= oncelik(stack.peek()))
result += stack.pop();
stack.push(c);
}
}
while (!stack.isEmpty())
result += stack.pop();
return result;
}
static int evaluatePostfix(String exp)
{
YigitI stack=new YigitI(100);
for(int i=0;i<exp.length();i++)
{
char c=exp.charAt(i);
if(Character.isDigit(c))
stack.push(c -'0');
else
{
int val1 = stack.pop();
int val2 = stack.pop();
switch(c)
{
case '+':
stack.push(val2+val1);
break;
case '-':
stack.push(val2- val1);
break;
case '/':
stack.push(val2/val1);
break;
case '*':
stack.push(val2*val1);
break;
}
}
}
return stack.pop();
}
static int evaluateprefix(String exp){
YigitI stack=new YigitI(100);
for(int i=exp.length()-1;i>=0;i--)
{
char c=exp.charAt(i);
if(Character.isDigit(c))
stack.push(c -'0');
else
{
int val1 = stack.pop();
int val2 = stack.pop();
switch(c)
{
case '+':
stack.push(val2+val1);
break;
case '-':
stack.push(val1- val2);
break;
case '/':
stack.push(val1/val2);
break;
case '*':
stack.push(val2*val1);
break;
}
}
}
return stack.pop();
}
public static void main(String[] args)
{
String exp = "(3+8)*5-7/2";
String prefix=infixToPrefix(exp);
String postfix=infixToPostfix(exp);
System.out.println(exp+" ifadesinin prefixi:"+prefix);
System.out.println(exp+" ifadesinin postfixi:"+postfix);
System.out.println(evaluatePostfix(postfix));
System.out.println(evaluateprefix(prefix));
}
}