CODEWITHSUNDEEP
c++
Clayton
Clayton

Reputation: 3

C++ class does not output correct data?

No compilation error but the output is this:

g++ class.cpp && ./a.out
is -1003073000 years old.

It does not output the string and int as it supposed to be.

I don't know what is wrong, I would really appreciate if someone point out my mistake, thanks!.

Here is the code:

#include<iostream>

class Student{
private:
        std::string name;
        int age;
public:
        Student(std::string name, int age){
                name = name;
                age = age;
        }
        void setName(std::string name){
                name = name;
        }
        std::string getName(){
                return name;
        }
        void setAge(int age){
                age = age;
        }
        int getAge(){
                return age;
        }
};

int main(){
        Student student1 = Student("Clayton",20);
        std::cout<<student1.getName();<<" is "<< student1.getAge()<<" years old."<<std::endl;
}

Upvotes: 0

Views: 55

Answers (1)

Some programmer dude
Some programmer dude

Reputation: 409166

In the constructor

Student(std::string name, int age){
        name = name;
        age = age;
}

The names name and age are the argument variables of those names. Which means you assign the variables to themselves.

That will leave the Student::name member default constructed and empty, but the Student::age variable will be uninitialized, and have an indeterminate value, and using such values (even printing them) is undefined behavior.

You have two solutions:

  1. Use this to explicitly reference the current object and use its member variables:

    Student(std::string name, int age){
    this->name = name;
    this->age = age;
}

  2. Or use a member initializer list to initialize (rather than assign to) the member variables:

    Student(std::string name, int age) : name(name), age(age) {
    // Empty
}

    For this the language knows the difference between the member and argument variables.

I highly recommend the second alternative.

Upvotes: 3

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