Why Is Returning a C String Literal from a `std::string` Function Problematic in C ?

Returning C String Literal from std::string Function: A Deeper Dive

In C , it's crucial to understand the implications of returning C string literals from std::string functions. Let's delve into why the following code snippet is problematic:

<br>std::string myFunction()<br>{</p>
<pre class="brush:php;toolbar:false">return "it's me!!";

}

The Potential Pitfall

Your initial analysis is accurate: the return statement implicitly invokes the std::string constructor with a const char[]. The returned string becomes a temporary object that should be destroyed upon function exit.

But Why Does It Work?

Running this code often doesn't cause any glaring errors because of a phenomenon known as undefined behaviour. When undefined behaviour occurs, the program's execution becomes unpredictable, and anything can happen.

In this case, the memory used for the temporary string, even though it's no longer referenced, may still retain its contents when accessed through c_str(). This is because the OS often doesn't clear out de-allocated memory but simply marks it as available for reuse.

Conclusion

While the code might seem to function correctly, it relies on undefined behaviour. This means that relying on this behaviour can lead to unpredictable and unreliable results. It's critical to understand the implications of returning C string literals from std::string functions and avoid undefined behaviour by ensuring proper memory management practices.

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