Numbers as Booleans

This is a really interesting question that goes back to how computers fundamentally work with true and false values. Let's break it down:

The Historical Reason

In early computers, there was no special boolean type - programmers used regular numbers to represent true and false. They needed a consistent rule for which numbers meant true and which meant false. The simplest rule was:

• 0 means false (nothing, absence of a value)
• Any other number means true (presence of a value)

This tradition carried forward into C, and then into C++, even after C++ added the bool type.

Why This Makes Sense

This convention actually turns out to be really useful in practice. Here's an example:

1#include <iostream>
2using namespace std;
3
4int main() {
5  int PlayerHealth{100};
6
7  // We can use PlayerHealth directly in an
8  // if statement
9  if (PlayerHealth) {
10    cout << "Player is alive!\n";
11  }
12
13  // Later in the game, player takes damage...
14  PlayerHealth = 0;
15
16  if (PlayerHealth) {
17    cout << "Player is alive!";
18  } else {
19    cout << "Game Over!";
20  }
21}

1Player is alive!
2Game Over!

In this example, we can check if the player is alive just by checking if their health is non-zero. We don't need to write if (PlayerHealth > 0) - though that would work too!

Real World Examples

This pattern shows up in many real-world programming scenarios:

• Checking if we found something (0 means not found)
• Checking if a calculation succeeded (0 means failed)
• Checking if a player has any resources left (0 means empty)
• Checking if an error occurred (0 means no error)

The pattern is so useful that many modern programming languages have adopted it, even ones that weren't based on C or C++.