Here are a few title options that fit the question-and-answer format, based on your article\'s content: **Option 1 (Focus on choice between const and const reference):** * **Const or Const Reference

Understanding const and const References in Function Arguments

In C , const can be used to guarantee that an object will not be modified within a function. However, when should you use const as an argument and when should you use a const reference instead?

Const References vs. Pointers

When passing an object by reference, you can specify if the reference can or cannot modify the object using const. Compared to passing a pointer, const references:

• Maintain the same call syntax (e.g., call(obj))
• Allow for passing null values (when using pointers)

Const References vs. Passing by Value

When deciding between const references and passing by value, consider the object's size and copy cost.

• Pass by value: Cheap to copy types are typically passed by value (e.g., primitive types).
• Const references: If you need to make a copy within the function, pass it by const reference.

Const Pointers vs. Non-Modifying Overloads

For optional parameters, you can use a const pointer to specify that the parameter can be null or provide overloads for different cases:

• Const pointer: Use if you want to be able to pass null (e.g., optional(myObject, nullptr))
• Overloads: Use if you want to have different functionality depending on whether the parameter is provided (e.g., optional(); optional(myObject);)

Const By Value as an Implementation Detail

When passing by value, const is purely an implementation detail. The following functions are the same:

<code class="cpp">void f(T);
void f(T const);</code>

This allows for flexibility in passing arguments while maintaining function identity.

The above is the detailed content of Here are a few title options that fit the question-and-answer format, based on your article\'s content: **Option 1 (Focus on choice between const and const reference):** * **Const or Const Reference. For more information, please follow other related articles on the PHP Chinese website!