Discussion: Going Global
Execute the code to understand the output and gain insights into global variables.
We'll cover the following...
Run the code
Now, it’s time to execute the code and observe the output.
Press + to interact
#include <iostream>int id;int main(){std::cout << id;}
Understanding the output
This puzzle looks similar to the Hack the Planet! puzzle; they both use the value of an uninitialized variable id. However, this is not an undefined behavior, and the program prints 0. Why is that?
Local vs. non-local variables
The difference is that the id variables in the “Hack the Planet!” puzzle are local variables, which pop in and out of existence each time the functions are called. They’re said to have automatic storage duration. The id in this puzzle, on the other hand, is a global variable. More precisely, id is a ...