1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 | import java.io.*; class stack { char stack1[]=new char[20]; int top; void push(char ch) { top++; stack1[top]=ch; } char pop() { char ch; ch=stack1[top]; top--; return ch; } int pre(char ch) { switch(ch) { case '-':return 1; case '+':return 1; case '*':return 2; case '/':return 2; } return 0; } boolean operator(char ch) { if(ch=='/'||ch=='*'||ch=='+'||ch=='-') return true; else return false; } boolean isAlpha(char ch) { if(ch>='a'&&ch<='z'||ch>='0'&&ch=='9') return true; else return false; } void postfix(String str) { char output[]=new char[str.length()]; char ch; int p=0,i; for(i=0;i<str.length();i++) { ch=str.charAt(i); if(ch=='(') { push(ch); } else if(isAlpha(ch)) { output[p++]=ch; } else if(operator(ch)) { if(stack1[top]==0||(pre(ch)>pre(stack1[top]))||stack1[top]=='(') { push(ch); } } else if(pre(ch)<=pre(stack1[top])) { output[p++]=pop(); push(ch); } else if(ch=='(') { while((ch=pop())!='(') { output[p++]=ch; } } } while(top!=0) { output[p++]=pop(); } for(int j=0;j<str.length();j++) { System.out.print(output[j]); } } } class intopost { public static void main(String[] args)throws Exception { String s; BufferedReader br=new BufferedReader(new InputStreamReader(System.in)); stack b=new stack(); System.out.println("Enter input string"); s=br.readLine(); System.out.println("Input String:"+s); System.out.println("Output String:"); b.postfix(s); } } |
Output:
Enter input string
a+b*c
Input String:a+b*c
Output String:
abc*+
Enter input string
a+(b*c)/d
Input String:a+(b*c)/d
Output String:
abc*d/)(+
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February 9th, 2012 at 12:40 pm
Please could you repair the code, cause I’m having trouble with the “Open and closed Parenthesis”. when I input an infix with parenthesis in it. the result is wrong ..
((