C++ Pointers: Solving "g is not defined" & "return" Meaning

[beatlesben]

Hello, I'm teaching myself C++. I'm pretty much at level one. Anyway I was trying to make a code, playing with pointers:

#include <iostream>

using namespace std;

int main()
{
int x;
int g;
int *p;
x = 1 + g;
cin>> g;
p = &x;
cin.ignore();
cout<< *p <<"\n";
cin.get();
return 1;
}


When I run the code it says that g is not defined, but g is what you have to enter, so I don't understand how to define it.

Also could someone explain "return." I don't understand what the value next to it means.

Thanks,
Remember, this is my second day of learning this...

 

[gb7nash]

Hello, I'm teaching myself C++. I'm pretty much at level one. Anyway I was trying to make a code, playing with pointers:

#include <iostream>

using namespace std;

int main()
{
int x;
int g;
int *p;
x = 1 + g;
cin>> g;
p = &x;
cin.ignore();
cout<< *p <<"\n";
cin.get();
return 1;
}


When I run the code it says that g is not defined, but g is what you have to enter, so I don't understand how to define it.

Also could someone explain "return." I don't understand what the value next to it means.

Thanks,
Remember, this is my second day of learning this...

Hi Beatlesben,

You've properly declared the variable g as integer, so that's set aside a piece of memory for the variable g. However, you have not specified the value of g until:

cin>> g;

When you get to the line of code that says:

x = 1 + g;

C++ does not have a value for g at this time. To fix this, make sure to put the

cin>> g;

before the:

x = 1 + g;

This way, you'll properly read in the value and place it into the variable g, and then you can use g for any future calculations.


----

As a side note, you're already teaching yourself pointers and address references? You must be a fast learner.

 

[DavidSnider]

You're assigning x to 1 + g before g has been read.

Also return 1 typically means failure while 0 is success. A better approach is to #include <cstdlib> and return EXIT_SUCCESS

 

[beatlesben]

Thanks for the quick responses.
It worked perfectly!

 

[LudusRex]

Hello! Congrats on teaching yourself C++! Pointers can be tricky to understand at first, so don't worry if you're having trouble with them.

In your code, you have declared two variables: x and g. However, you have not given a value to g before trying to use it in your code. This is why you are getting the error "g is not defined". To fix this, you need to ask the user to input a value for g before using it in your code. You can do this by using the cin function, as you have done with x. So your code should look something like this:

#include <iostream>

using namespace std;

int main()
{
int x;
int g;
int *p;
cout << "Please enter a value for g: ";
cin >> g;
x = 1 + g;
p = &x;
cout << *p << "\n";
cin.ignore();
cin.get();
return 1;
}

Now, when you run the code, it will ask for a value for g before using it in the calculation.

As for the "return" statement, it is used to indicate the end of a function. In your code, the main function is declared as an int (integer) function, which means it is expected to return an integer value. In this case, the value 1 is being returned. This value is typically used to indicate if the program ran successfully (1) or encountered an error (0). So in your code, the return statement is just indicating that the main function has ended and the program can terminate.

I hope this helps clarify things for you. Keep up the good work with learning C++!