quaint jetty
Ive tried writing a code which takes in postfix expression as a string converts it into an expression tree through function pfxtoexpt and passes the expression tree returned to another function expttoprefix which is supposed to return the corr prefix expression
Im not getting any errors but im not able to get the prefix expression as output
Im attaching the screenshot of class node treenode and stack
string expttoprefix(TreeNode* root){
string prefixexp;
if (root!=NULL){
prefixexp+=root->value;
if (root->lt!=NULL)
{prefixexp+=expttoprefix(root->lt);}
if (root->rt!=NULL)
{prefixexp+=expttoprefix(root->rt);}
}
return prefixexp;
}
TreeNode* pfxtoexpt(const string& pfx){
Stack<TreeNode*> mystack;
const char* ptr=pfx.c_str();
while(ptr!=NULL){
if(isalnum(ptr)){
mystack.push(new TreeNode(ptr));
}
else{
TreeNode rightop=mystack.getTop();
mystack.pop();
TreeNode leftop= mystack.getTop();
mystack.pop();
TreeNode opnode=new TreeNode(ptr);
mystack.pop();
opnode->lt=leftop;
opnode->rt=rightop;
mystack.push(opnode);}}
return mystack.getTop();
}
int main(){
string postfixexp;
cout<<"Enter the postfix expression:";
std::getline(cin,postfixexp);
TreeNode expressiontree=pfxtoexpt(postfixexp);
cout<<"Prefix expression:"<<expttoprefix(expressiontree)<<endl;
return 0;
};
dense flint