programing to confirm prefix to postfix in c++

1 ANSWERS

1. amomipais82
   

   Hi There,
   #include<stdio.h>
   #include<conio.h>
   #include<string.h>
   #define MAX 20
   
   char stack[MAX];
   int top = -1;
   char pop();
   void push(char item);
   
   int prcd(char symbol) {
   
   switch(symbol) {
   
   case '+':
   case '-':
   
   return 2;
   
   case '*':
   case '/':
   
   return 4;
   
   case '^':
   case '$':
   
   return 6;
   
   case '(':
   case ')':
   case '#':
   
   return 1;
   
   }
   
   }
   
   int isoperator(char symbol) {
   
   switch(symbol) {
   
   case '+':
   case '-':
   case '*':
   case '/':
   case '^':
   case '$':
   case '(':
   case ')':
   
   return 1;
   
   default:
   
   return 0;
   
   }
   
   }
   
   void convertip(char infix[],char prefix[]) {
   
   int i,symbol,j=0;
   char test[MAX];
   
   infix=strrev(infix);
   stack[++top]='#';
   
   for(i=0;i<strlen(infix);i++) {
   
   symbol=infix[i];
   if(isoperator(symbol)==0) {
   
   prefix[j]=symbol;
   j++;
   
   }else {
   
   if(symbol==')') {
   
   push(symbol);
   
   }else if(symbol=='(') {
   
   while(stack[top]!=')') {
   
   prefix[j]=pop();
   j++;
   
   }
   pop();//pop out (.
   
   }else {
   
   if(prcd(symbol)>prcd(stack[top])) {
   
   push(symbol);
   
   }else {
   
   while(prcd(symbol)<=prcd(stack[top])) {
   
   prefix[j]=pop();
   j++;
   
   }
   push(symbol);
   
   }//end of else.
   
   }//end of else.
   
   }//end of else.
   
   }//end of for.
   
   while(stack[top]!='#') {
   
   prefix[j]=pop();
   j++;
   
   }
   prefix[j]='\0';//null terminate string.
   prefix=strrev(prefix);
   
   }
   
   int main() {
   
   char infix[20],prefix[20];
   clrscr();
   printf("Enter the valid infix string:\n");
   gets(infix);
   convertip(infix,prefix);
   printf("The corresponding prefix string is:\n");
   puts(prefix);
   getch();
   
   return 0;
   
   }
   
   void push(char item) {
   
   top++;
   stack[top]=item;
   
   }
   
   char pop() {
   
   char a;
   a=stack[top];
   top--;
   return a;
   
   }
   
   Thanks

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