Question: I need to change the expression class tree constructor to expression_tree(istream&); I have the expression_tree.h file and the expressionTree_tester.cpp file. Could someone please change the
I need to change the expression class tree constructor to expression_tree(istream&);
I have the expression_tree.h file and the expressionTree_tester.cpp file. Could someone please change the parameterized constructor to the one above and make it run in the test file.
********expression_tree.h***************
#include
#include
#include
#include
#include
struct exp_node
{
int number;
char * op;
exp_node *left_field, *right_field;
};
exp_node *root, *temp;
int eval(exp_node*);
void display(exp_node*);
using namespace std;
class expression_tree
{
expression_tree()
{
root = NULL;
root->left_field = NULL;
root->right_field = NULL;
}
expression_tree(char str)
{
exp_node *nnode, *temp;
nnode = new exp_node;
nnode->left_field = NULL;
nnode->right_field = NULL;
if ((int)str>48 && (int)str <= 56)
{
nnode->number = (int)str - 48;
}
else
{
nnode->number = 0;
strcpy(nnode->op, str);
}
if (root == NULL)
{
root = nnode;
}
else
{
while (1)
{
if (temp->right_field == NULL)
{
temp->right_field = nnode;
if (nnode->number == 0)
{
temp = temp->right_field;
}
break;
}
else if (temp->left_field == NULL)
{
temp->left_field = nnode;
if (nnode->number == 0)
{
temp = temp->left_field;
}
break;
}
else
{
temp = root;
while (temp->left_field != NULL)
temp = temp->left_field;
temp->left_field = nnode;
if (nnode->number == 0)
{
temp = temp->left_field;
}
break;
}
}
}//else
}
void display(exp_node *temp)
{
if (temp != NULL)
{
display(temp->left_field);
if (temp->number == 0)
cout << endl << temp->op;
else
cout << endl << temp->number;
display(temp->right_field);
}
}
int evaluate(exp_node *temp)
{
int l = 0; int o1, o2, res = 0; char a;
if (temp != NULL)
{
o1 = evaluate(temp->left_field);
if (temp->number != 0)
return temp->number;
else
{
o2 = evaluate(temp->right_field);
if (temp->number != 0)
return temp->number;
else
{
if ((int)temp->op == 43)
res = o1 + o2;
else if ((int)temp->op == 42)
res = o1*o2;
else if ((int)temp->op == 45)
res = o1 - o2;
else if ((int)temp->op == 47)
res = o1 / o2;
return res;
}
}
}
}
public:
exp_node* get_root()
{
return root;
}
};
*************expressionTree_tester.cpp****************************
#include "expression_tree.h"
#include
#include
#include
#include
using namespace std;
// displays binary expression tree
void pretty_print(const exp_node* node_ptr, int depth = 5)
// Library facilities used: iomanip, iostream
{
cout << setw(4 * depth) << ""; // indentation
if (node_ptr == nullptr) {
// fallen off the tree
cout << "[Empty]" << std::endl;
}
else if (node_ptr->left_field == nullptr) {
// a leaf with numeric data
cout << node_ptr->number;
cout << " [leaf]" << std::endl;
}
else {
// a nonleaf with operator
cout << node_ptr->op << std::endl;
pretty_print(node_ptr->right_field, depth + 1);
pretty_print(node_ptr->left_field, depth + 1);
}
}
// main interactive testing function
int main() {
cout << "Enter the postfix expression: ";
while (cin && cin.peek() != ' ') {
// allocate memory
expression_tree *expTree = new expression_tree(cin);
// display binary tree
pretty_print(expTree->get_root());
cout << " \t==> evaluates to " << eval(expTree->get_root()) << endl;
// release memory
delete expTree;
// clear input stream
cin.ignore();
cout << "Enter another postfix expression or
}
cout << "This concludes the Binary Tree Math Postfix Expression program! ";
return EXIT_SUCCESS;
}
********************************************************************************************
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