Linked List problem in displaying the result

[oj1C54Gy]

I encountered a problem every time I try to run this code random numbers will always appear

#include<iostream>

using namespace std;

struct dataType{
string name;
int age;

dataType *next;
};

dataType *head, *pnew, *pc;

int main(){


//initialize
head = new dataType;
head -> next = NULL;
pc = head;

//add
for(char ans= 'y' ;ans != 'n';){

pnew = new dataType;
pc-> next = pnew;

cout<<"Name: ";
cin>>pnew -> name;
cout<<"Age: ";
cin>>pnew -> age;

pnew -> next = NULL;
pc = pnew;

cout<<"\n Do you want to add record? (y/n)";
cin>>ans;
}

//display
pc = head;
while (pc != NULL){

cout << pc->name << "\t" << pc->age << endl;
pc = pc->next;

}
system("pause");
return 0;

}

result:

Name: jay
Age: 21

Do you want to add record? (y/n)y
Name: rick
Age: 56

Do you want to add record? (y/n)y
Name: jade
Age: 20

Do you want to add record? (y/n)n
-842150451 //This is what I mean
jay 21
rick 56
jade 20

[The Grey Wolf]

When you come to display, you are setting pc to point to the head object and you want to point it to the object that head points to...

    //display
    pc = head->next;
    while (pc != NULL) {

[seeplus]

A more 'normal' implementation is to have head point to the first node - not being a distinct node with no data. Perhaps:

#include <iostream>
#include <string>

struct dataType {
	std::string name;
	int age {};

	dataType* next {};
};

int main() {
	dataType* head {};

	for (char ans = 'y'; ans != 'n'; ) {
		const auto pnew {new dataType};

		std::cout << "Name: ";
		std::cin >> pnew->name;

		std::cout << "Age: ";
		std::cin >> pnew->age;

		pnew->next = head;
		head = pnew;

		std::cout << "\nDo you want to add record? (y/n): ";
		std::cin >> ans;
	}

	for (auto pc {head}; pc != nullptr; pc = pc->next)
		std::cout << pc->name << "\t" << pc->age << '\n';
}

[oj1C54Gy]

I also need to display the highest number so I added

int max = INT_MAX;

	if (max > pc->age)
	   max = pc->age;

but its not working

[The Grey Wolf]

Try initialising max to zero not INT_MAX. int max = 0; or int max{}; etc.

[againtry]

#include<iostream>

using namespace std;

struct DataNode
{
    string name;
    int age{-99};
    
    DataNode *next;
};

int main()
{
    DataNode* head{nullptr};
    DataNode* pnew{nullptr};
    DataNode* pc{nullptr};
    
    //initialize
    head = new DataNode;
    head -> next = nullptr;
    pc = head;
    
    //add
    for(char ans= 'y' ;ans != 'n';)
    {
        pnew = new DataNode;
        pc-> next = pnew;
        
        cout<<"Name: ";
        cin>>pnew -> name;
        cout<<"Age: ";
        cin>>pnew -> age;
        
        pnew -> next = nullptr;
        pc = pnew;
        
        cout<<"\n Do you want to add record? (y/n)";
        cin>>ans;
    }
    
    //display
    int max_age{0};
    
    pc = head -> next;
    while (pc != nullptr)
    {
        if(pc->age > max_age)
            max_age = pc->age;
           
           cout << pc->name << "\t" << pc->age << endl;
        pc = pc->next;
    }
    
    cout << "Maximum age: " << max_age << '\n';
    
    return 0;
}

Name: aa
Age: 11

 Do you want to add record? (y/n)y
Name: bb
Age: 7

 Do you want to add record? (y/n)y
Name: cc
Age: 14

 Do you want to add record? (y/n)n
aa	11
bb	7
cc	14
Maximum age: 14
Program ended with exit code: 0