C program to convert Infix to Postfix Expression using Stack
Simple C program to convert Infix to Postfix Expression using Stack.
Code:
#include<stdio.h>#include<conio.h>
#include <ctype.h>
char s[50];
int top=-1;
push(char elem)
{
s[++top]=elem;
}
char pop()
{
return(s[top--]);
}
int pr(char elem)
{
switch(elem)
{
case '#': return 0;
case '(': return 1;
case '+':
case '-': return 2;
case '*':
case '/': return 3;
}
}
main()
{
char infx[50],pofx[50],ch,elem;
int i=0,k=0;
clrscr();
printf("\n\nEnter the infix Expression: ");
scanf("%s",infx);
push('^');
while( (ch=infx[i++]) != '\0')
{
if( ch == '(') push(ch);
else
if(isalnum(ch)) pofx[k++]=ch;
else
if( ch == ')')
{
while( s[top] != '(')
pofx[k++]=pop();
elem=pop();
}
else
{
while( pr(s[top]) >= pr(ch) )
pofx[k++]=pop();
push(ch);
}
}
while( s[top] != '^')
pofx[k++]=pop();
pofx[k]='\0';
printf("\n\nGiven Infix Expression: %s \nPostfix Expression: %s\n",infx,pofx);
getch();
}
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