How do I pass a const reference?

When you pass by const reference, you take the argument in by reference (avoiding making any copies of it), but cannot make any changes to the original object (much as would happen when you would take the parameters in by value).

How do you pass a constant reference in C++?

When passing an argument by reference, always use a const reference unless you need to change the value of the argument. Non-const references cannot bind to r-values. A function with a non-const reference parameter cannot be called with literals or temporaries.

What is const reference in C++?

– const references allow you to specify that the data referred to won’t be changed. A const reference is actually a reference to const. Once a reference is bound to refer to an object, it can not be bound to refer to another object.

Why do we pass or return variables by const * or const&?

We pass by const reference to avoid making a copy of the object. When you pass a const reference, you pass a pointer (references are pointers with extra sugar to make them taste less bitter). And assuming the object is trivial to copy, of course.

Is const reference faster?

One of those fast types is std::string_view . If you’re uncertain if a non-fundamental type is fast to pass by value, pass it by const reference. Pass non-pointer, non-fundamental data type variables (such as structs) by (const) reference, unless you know that passing it by value is faster.

What is a pass by reference in C++?

Pass-by-reference means to pass the reference of an argument in the calling function to the corresponding formal parameter of the called function. The called function can modify the value of the argument by using its reference passed in. The formal parameter is an alias for the argument. …

Can you modify a const reference C++?

But const (int&) is a reference int& that is const , meaning that the reference itself cannot be modified.

What is the difference between pointers and references in C++?

Differences between pointers and references in C++ A pointer in C++ is a variable that holds the memory address of another variable. A reference is an alias for an already existing variable. Once a reference is initialized to a variable, it cannot be changed to refer to another variable.

Is const reference faster than reference?

If you’re uncertain if a non-fundamental type is fast to pass by value, pass it by const reference. Pass non-pointer, non-fundamental data type variables (such as structs) by (const) reference, unless you know that passing it by value is faster.

Do you need to pass an array by reference in C++?

Because arrays are already pointers, there is usually no reason to pass an array explicitly by reference. For example, parameter A of procedure zero above has type int*, not int*&. The only reason for passing an array explicitly by reference is so that you can change the pointer to point to a different array.