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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. int precedence(char);
  5. struct node{
  6.         char i;
  7.         node *next;
  8.     }*ptr,*newptr,*a,*top;
  9. class stack{
  10.     node *create_node(char data){
  11.     ptr=new node;
  12.     ptr->i=data;
  13.     ptr->next=NULL;
  14.     return ptr;
  15.     }
  16.     public:
  17.     void push(char d);
  18.     void pop();
  19.     bool isempty();
  20.     void display(node *np){
  21.         while(np!=NULL){
  22.             cout<<np->i;
  23.             np=np->next;
  24.         }
  25.         cout<<"\n";
  26.     }
  27.     };
  28.     void stack::push(char d){
  29.         newptr=create_node(d);
  30.         if(isempty()){top=newptr;}
  31.         else{
  32.             newptr->next=top;
  33.             top=newptr;
  34.         }
  35.  
  36.     }
  37.     void stack::pop(){
  38.          if(isempty()){cout<<"underflow";}
  39.     else{
  40.         a=top;
  41.         top=top->next;
  42.         delete a;
  43.     }
  44.     }
  45.     bool stack::isempty(){
  46.         if(top==NULL){return true;}
  47.         else return false;
  48.     }
  49.     int main(){
  50.         int size,em=0;
  51.         stack s1;
  52.         cin>>size;
  53.         char vop,infix[size],postfix[size];
  54.         for(int E=0;E<size;E++){
  55.             cin>>vop;
  56.             infix[E]=vop;
  57.     for(int e=0;e<size;e++){
  58.         if((infix[e]>='a'&&infix[e]<='z')||(infix[e]>='A'&&infix[e]<='Z')){
  59.             postfix[em]=infix[e];
  60.             em++;
  61.         }
  62.         else if(infix[e]=='('){
  63.             s1.push(infix[e]);
  64.         }
  65.         else if(infix[e]==')'){
  66.             while(!s1.isempty()&&top->i!='('){
  67.                 postfix[em]=top->i;
  68.                 em++;
  69.                 s1.pop();
  70.             }
  71.         s1.pop();    
  72.         }
  73.         else
  74.         {
  75.           while(!s1.isempty()&&top->i!='('&&precedence(top->i)>=precedence(infix[e]))
  76.            {
  77.             postfix[em]=top->i;
  78.             em++;
  79.             s1.pop();
  80.            }
  81.             s1.push(infix[e]);
  82.         }
  83.     }  
  84.     while(!s1.isempty()){
  85.         postfix[em]=top->i;
  86.         s1.pop();
  87.         em++;
  88.     }
  89. for(int ele=0;ele<size;ele++){
  90.     cout<<postfix[ele];
  91. }
  92.        return 0;     
  93.     }    
  94.     int precedence(char c){
  95.     switch(c){
  96.  
  97.         case '^': return 5;
  98.                   break;
  99.         case '/':return 4;
  100.                     break;
  101.         case '*':return 4;
  102.                   break;
  103.  
  104.         case '-':return 3;
  105.                    break;
  106.         case '+':return 3;
  107.                   break;
  108.  
  109.     }
  110. }
Compilation error #stdin compilation error #stdout 0s 0KB
comments (?)
stdin
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Standard input is empty
compilation info 
prog.cpp: In function ‘int main()’:
prog.cpp:94:27: error: a function-definition is not allowed here before ‘{’ token
     int precedence(char c){
                           ^
prog.cpp:110:1: error: expected ‘}’ at end of input
 }
 ^
stdout
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Standard output is empty
https://ideone.com/SI2w7l
language:
C++ (gcc 8.3)
created:
5 years ago
visibility:
public

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