112 lines
2.1 KiB
C++
112 lines
2.1 KiB
C++
#include<iostream>
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#include<ctype.h>
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using namespace std;
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class stack
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{
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int top;
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char data[20];
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public:
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stack()
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{
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top=-1;
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}
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void conversion(char infix[20],char postfix[20])
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{
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int j=0,i;
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char e,token,x;
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for(i=0;infix[i]!='\0';i++)
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{
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token=infix[i];
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if(isalnum(token))
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{
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postfix[j]=token;
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j++;
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}
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else
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{
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if(token=='(')
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push(token);
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else if(token==')')
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{
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while((x=pop())!='(')
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{
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postfix[j]=x;
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j++;
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}
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}
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else
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{
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e=topmost();
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while(precedence(token)<=precedence(e) && !empty())
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{
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x=pop();
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postfix[j]=x;
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j++;
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}
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push(token);
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}
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}
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}
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while(!empty())
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{
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x=pop();
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postfix[j]=x;
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j++;
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}
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postfix[j]='\0';
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}
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void push(int x)
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{
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top++;
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data[top]=x;
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}
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int pop()
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{
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char x;
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x=data[top];
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top--;
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return x;
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}
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char topmost()
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{
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char e;
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e=data[top];
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return e;
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}
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int precedence(char x)
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{
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if(x=='(')
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return 0;
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if(x=='+'|| x=='-')
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return 1;
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if(x=='*'|| x=='/' ||x=='%')
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return 2;
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else
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return 3;
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}
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int empty()
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{
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if(top==-1)
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return 1;
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else
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return 0;
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}
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};
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int main()
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{
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stack s;
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char infix[20],postfix[20];
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cout<<"Enter the infix expression: ";
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cin>>infix;
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s.conversion(infix,postfix);
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cout<<"Post fix expression is: "<<postfix;
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return 0;
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}
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