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DS/C/Lab/Week11/expression.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include<stdbool.h>
+#include<ctype.h>
+#include<string.h>
+#define MAX 100
+
+typedef struct TNode *Tptr;
+typedef struct TNode
+{
+    char data;
+    Tptr leftchild;
+    Tptr rightchild;
+}TNode;
+///*
+//Create nodes in the tree
+Tptr createNode(char val)
+{
+    Tptr temp =(Tptr)malloc(sizeof(TNode));
+    temp->data = val;
+    temp->leftchild = temp->rightchild = NULL;
+    return temp;
+}
+//*/
+
+Tptr stack[MAX];
+int top=-1;
+int i;
+
+//check if stack is empty
+bool isEmpty()
+{
+    return top==-1;
+}
+
+//check if stack is full
+bool isFull()
+{
+    return top==MAX -1;
+}
+
+//push element onto stack
+void Push(Tptr e)
+{
+    if(isFull())
+    {
+        return;
+    }
+    stack[++top]=e;
+}
+
+//pop element from stack
+Tptr Pop()
+{
+    Tptr popped=createNode('\0');
+    if(isEmpty())
+    {
+        free(popped);
+    }
+    else
+    {
+        popped=stack[top--];
+    }
+    return popped;
+}
+
+//check if character is operator
+bool isOperator(char ch)
+{
+    bool ret=false;
+    if(ch=='*' || ch=='/' || ch=='+' || ch=='-' || ch=='^' )
+    {
+        ret = true;
+    }
+    return ret;
+}
+
+Tptr createExpression(char* postfix)
+{
+    int i;
+    int plen =strlen(postfix);
+    char cc;
+    for(i=0;i<plen;i++)
+    {
+        cc = postfix[i];
+        if(isalnum(cc))
+        {
+            Tptr node = createNode(cc);
+            Push(node);
+        }
+        else if(isOperator(cc))
+        {
+            Tptr node = createNode(cc);
+            node->rightchild = Pop();
+            node->leftchild = Pop();
+            Push(node);
+        }
+    }
+    return stack[top];
+}
+
+void inOrderTraversal(Tptr root)
+{
+    if (root != NULL)
+    {
+        inOrderTraversal(root->leftchild);
+        printf("%c ", root->data);
+        inOrderTraversal(root->rightchild);
+    }
+}
+
+int main()
+{
+    char postfix[] = "ab*cd/-";
+    Tptr expressionTree = createExpression(postfix);
+
+    if (expressionTree != NULL)
+    {
+        printf("In-Order Traversal of the Expression Tree: ");
+        inOrderTraversal(expressionTree);
+        printf("\n");
+    }
+
+    return 0;
+}