INFIX TO POSTFIX USING STACK IN C(PARENTHESES).

DOWNLOAD FULL PROGRAME

CODING:
#include<stdio.h>
#include<conio.h>
#define max 50
char st[max];
int top=-1;
void push(char st[],char);
char pop(char st[]);
void intopostex(char source[],char target[]);
int getpriority(char);
void main()
{
char infix[50],postfix[50];
clrscr();
printf("\nENTER INFIX EXPRESSION:\n");
fflush(stdin);
gets(infix);
strcpy(postfix,"");
intopostex(infix,postfix);
printf("\nTHE POSTFIX EXPRESSION:\n");
puts(postfix);
getch();
}
void intopostex(char sourse[],char target[])
{
int i=0,j=0;
char temp;
strcpy(target,"");
while(sourse[i]!='\0')
 {
  if(sourse[i]=='(')
   {
    push(st,sourse[i]);
    i++;
   }
  else if(sourse[i]==')')
   {
    while((top!=-1) && (st[top]!='('))
    {
     target[j]=pop(st);
     j++;
    }
    if(top==-1)
    {
     printf("\nINCORRECT EXPRESSION..");
     exit(1);
    }
    temp=pop(st);
    i++;
   }
  else if(isdigit(sourse[i]) || isalpha(sourse[i]))
   {
    target[j]=sourse[i];
    j++;
    i++;
   }
  else if(sourse[i]=='+' || sourse[i]=='-' || sourse[i]=='*' || sourse[i]=='/' || sourse[i]=='%')
   {
    while((top!=-1) && (st[top]!='(') && (getpriority(st[top])) > (getpriority(sourse[i])))
     {
     target[j]=pop(st);
     j++;
     }
     push(st,sourse[i]);
     i++;
   }
  else
   {
    printf("\nINCORRECT ELEMENT IN EXPRESSION");
    exit(1);
   }
 }
 while((top!=-1) && (st[top]!='('))
  {
   target[j]=pop(st);
   j++;
  }
  target[j]='\0';
}
int getpriority(char sign)
{
 if(sign=='/' || sign=='*' || sign=='%')
  return 1;
 else if(sign=='+' || sign=='-')
  return 0;
}
void push(char st[],char num)
{
 if(top==max-1)
   printf("\nSTACK IS OVERFLOW..");
 else
 {
   top++;
   st[top]=num;
 }
}
char pop(char st[])
{
char num=' ';
 if(top==-1)
   printf("\nSTACK IS UNDERFLOW..");
 else
 {
  num=st[top];
  top--;
 }
 return num;
}

//IN THIS PROGRAM TWO WARNINGS,BUT IT NOT AFFECT TO PROGRAM & NOT EFFICIENT.