What is const reference?
– const references allow you to specify that the data referred to won’t be changed. A const reference is actually a reference to const. A reference is inherently const, so when we say const reference, it is not a reference that can not be changed, rather it’s a reference to const.
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).
Does C pass constant reference?
C does not support references or passing by reference. You should use pointers instead and pass by address. Pass-by-value is efficient for primitive types, but does a shallow copy for structs. In C++ it makes a LOT of sense to pass objects by reference for efficiency.
What does const do in C?
const values The const keyword specifies that a variable’s value is constant and tells the compiler to prevent the programmer from modifying it. In C, constant values default to external linkage, so they can appear only in source files.
What is constant reference C++?
Constant References. A constant reference is really a reference to a constant. The use of const in a declaration of a reference (argument) means that we do not want to change the referenced object. “An initializer for const T& does not need to be an lvalue, or even of type T” The C++ Prog.
What is constant reference parameter?
The important difference is that when passing by const reference, no new object is created. In the function body, the parameter is effectively an alias for the object passed in. Because the reference is a const reference the function body cannot directly change the value of that object.
Should I always pass by reference?
if you want to change the stack object you are passing in, do so by ref. if you dont, pass it by value. if you dont wanna change it, pass it as const-ref. the optimization that comes with pass-by-value should not matter since you gain other things when passing as ref.
Should I always pass by const reference?
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.
When should you use a const reference parameter?
Where are constant qualifiers used?
When we don’t want to modify an argument and pass it as reference or pointer, we use const qualifier so that the argument is not accidentally modified in function. Class data members can be declared as both const and static for class wide constants. Reference variables can be const when they refer a const location.