/* C program to implement postfix expression tree and calculating its value */
#include<stdio.h>
#include<conio.h>
#include<alloc.h>
#include<stdlib.h>
#include<string.h>
struct tree
{
char data;
struct tree *left,*right;
};
int top=-1;
struct tree *stack[20];
struct tree *node;
void push(struct tree* node)
{
stack[++top]=node;
}
struct tree * pop()
{
return(stack[top--]);
}
/* Calculating the value of postfix expression using recursion */
int cal(struct tree *node)
{
int ch;
ch=check(node->data);
if(ch==1)
return node->data-48;
else if(ch==2)
{
if(node->data==+)
return cal(node->left)+cal(node->right);
if(node->data==-)
return cal(node->left)-cal(node->right);
if(node->data==*)
return cal(node->left)*cal(node->right);
if(node->data==/)
return cal(node->left)/cal(node->right);
}
}
/* Displaying all node in order */
void inorder(struct tree *node)
{
if(node!=NULL)
{
inorder(node->left);
printf("%c",node->data);
inorder(node->right);
}
}
/* Checking operator and operands */
int check(char ch)
{
if(ch==+||ch==-||ch==/||ch==*)
return 2;
else
return 1;
}
/* making simple operand node and pushing into stack */
void operand(char b)
{
node=(struct tree*)malloc(sizeof(struct tree));
node->data=b;
node->left=NULL;
node->right=NULL;
push(node);
}
/* making operator node than pop-up two nodes from stack and adding into operator node and finally push node into stack */
void operators(char a)
{
node=(struct tree*)malloc(sizeof(struct tree));
node->data=a;
node->right=pop();
node->left=pop();
push(node);
}
void main()
{
int i,p,k,ans;
char s[20];
clrscr();
printf("Enter the expression in postfix form
");
fflush(stdin);
gets(s);
k=strlen(s);
i=0;
for(i=0;s[i]!=
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#include<stdio.h>
#include<conio.h>
#include<alloc.h>
#include<stdlib.h>
#include<string.h>
struct tree
{
char data;
struct tree *left,*right;
};
int top=-1;
struct tree *stack[20];
struct tree *node;
void push(struct tree* node)
{
stack[++top]=node;
}
struct tree * pop()
{
return(stack[top--]);
}
/* Calculating the value of postfix expression using recursion */
int cal(struct tree *node)
{
int ch;
ch=check(node->data);
if(ch==1)
return node->data-48;
else if(ch==2)
{
if(node->data==+)
return cal(node->left)+cal(node->right);
if(node->data==-)
return cal(node->left)-cal(node->right);
if(node->data==*)
return cal(node->left)*cal(node->right);
if(node->data==/)
return cal(node->left)/cal(node->right);
}
}
/* Displaying all node in order */
void inorder(struct tree *node)
{
if(node!=NULL)
{
inorder(node->left);
printf("%c",node->data);
inorder(node->right);
}
}
/* Checking operator and operands */
int check(char ch)
{
if(ch==+||ch==-||ch==/||ch==*)
return 2;
else
return 1;
}
/* making simple operand node and pushing into stack */
void operand(char b)
{
node=(struct tree*)malloc(sizeof(struct tree));
node->data=b;
node->left=NULL;
node->right=NULL;
push(node);
}
/* making operator node than pop-up two nodes from stack and adding into operator node and finally push node into stack */
void operators(char a)
{
node=(struct tree*)malloc(sizeof(struct tree));
node->data=a;
node->right=pop();
node->left=pop();
push(node);
}
void main()
{
int i,p,k,ans;
char s[20];
clrscr();
printf("Enter the expression in postfix form
");
fflush(stdin);
gets(s);
k=strlen(s);
i=0;
for(i=0;s[i]!=
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