Added just to help other....
#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
#define Operator 1
#define notOperator 0
#define empty -1
void formatting(void);
void getInput(void);
int chkElement(char);
void opFunc(char);
void varFunc(char);
void push(struct node*);
struct node* pop(void);
void dispTree(void);
void infix(struct node*);
void prefix(struct node*);
void postfix(struct node*);
char equation[25];
struct node* stack[25];
int stackPtr = -1;
struct node{
char item;
struct node* leftChild;
struct node* rightChild;
};
struct node* root;
void main(void)
{
int count;
clrscr();
formatting();
getInput();
printf("\nYou have entered: ");
puts(equation);
for(count = 0; equation[count] != '\0'; count++)
{
switch(chkElement(equation[count]))
{
case Operator:
opFunc(equation[count]);
break;
case notOperator:
varFunc(equation[count]);
break;
default:
printf("\nSorry unrecognized entry");
}
}
dispTree();
getch();
}
void dispTree(void)
{
char choice;
printf("\nSelect the output form: [i]nfix, p[r]efix, p[o]stfix: ");
choice = getche();
printf("\n");
switch(choice)
{
case 'i':
printf("\nInorder representation of output is: ");
infix(stack[stackPtr]);
break;
case 'r':
printf("\nPreorder representation of output is: ");
prefix(stack[stackPtr]);
break;
case 'o':
printf("\nPostorder representation of output is: ");
postfix(stack[stackPtr]);
break;
default:
printf("\nYou have pressed the button other than given choices");
}
}
void infix(struct node* root)
{
if(root->leftChild != NULL) infix(root->leftChild);
printf("%c", root->item);
if(root->rightChild !=NULL) infix(root->rightChild);
}
void prefix(struct node* root)
{
printf("%c", root->item);
if(root->leftChild != NULL) prefix(root->leftChild);
if(root->rightChild !=NULL) prefix(root->rightChild);
}
void postfix(struct node* root)
{
if(root->leftChild != NULL) postfix(root->leftChild);
if(root->rightChild !=NULL) postfix(root->rightChild);
printf("%c", root->item);
}
void opFunc(char optr)
{
root = (struct node*)malloc(sizeof(struct node));
root->item = optr;
root->rightChild = pop();
root->leftChild = pop();
push(root);
}
struct node* pop(void)
{
return(stack[stackPtr--]);
}
void varFunc(char var)
{
root = (struct node*)malloc(sizeof(struct node));
root->item = var;
root->rightChild = NULL;
root->leftChild = NULL;
push(root);
}
void push(struct node* root)
{
stack[++stackPtr] = root;
}
int chkElement(char element)
{
switch(element)
{
case '+':
case '-':
case '*':
case '/':
case '%':
case '^':
return(Operator);
default:
return(notOperator);
}
}
void getInput(void)
{
printf("\n\nEnter equation in the form of postfix: ");
gets(equation);
}
void formatting(void)
{
int i;
printf("\n");
for(i =0; i<=79 ; i++)
printf("*");
printf("\n......... Prgogram title\t\t# Binary Tree");
printf("\n......... Created by\t\t # Romasa Qasim");
printf("\n......... Description\t\t # Creation of Expression Tree\n");
for( i =0; i<=79 ; i++)
printf("*");
}
