The Sneaky URL Trick: Why Your C++ Compiler Won’t Yell at You 🤫

Ever wondered if you could just… put a URL directly in your C++ code and have it compile? Sounds like it should explode with errors, right? Well, buckle up—it doesn’t. And the reason is hilariously clever.

The Magic Code

#include<iostream>
using namespace std;

int main() {
    https://www.toorun.dev/
    int x = 22;
    cout << x << endl;
    return 0;
}

This compiles. No errors. No warnings. It works perfectly. What’s going on?

The Secret: Goto Labels + Comments

Here’s the plot twist:

  • https is a goto label (anything followed by : in C++)
  • //www.toorun.dev/ is a comment (starts with //)

So the compiler reads it as:

https:           // This is a label (like a destination for goto)
//www.toorun.dev/  // This is a comment, ignored completely
int x = 22;      // Normal code continues

Why Does This Matter?

  1. Labels can appear almost anywhere – C++ allows you to label statements for use with goto
  2. Comments are invisible to the compiler – Everything after // is discarded
  3. The combination is unintentional brilliance – You can literally hide a URL in plain sight!

A More Deliberate Example

If you actually wanted to use the label (which you shouldn’t, goto is considered evil 😈):

#include<iostream>
using namespace std;

int main() {
    int x = 22;
    
    https://www.toorun.dev/blog/
    cout << x << endl;
    
    goto https; // Jump to the label above
    return 0;
}

Yes, this also compiles. And yes, it’s a chaotic mess. Please don’t do this in production code. 😅

The Lesson

C++ is wonderfully flexible—sometimes too flexible. This quirk is a great reminder that:

  • Labels in C++ are super permissive (they just need an identifier and :)
  • Comments eat everything after them (including what looks like URLs)
  • Fun tricks are fun, but readability is king â™›

So next time you see weird C++ behavior, remember: the compiler is probably doing exactly what it’s supposed to do. We’re just being creative (or chaotic) with it! 🚀

Pro tip: Use this knowledge to either amaze your friends or confuse your code reviewers. Choose wisely. 😎