Differences between C and C++ - references

January 26, 2025, by Slobodan Dmitrovic

When moving from C to C++, references or reference types are one of the first novelties we encounter. References are aliases for existing objects in memory.

The general syntax is:

reference_type& name = initializer;

Passing function arguments by a reference

In C++, we can pass function arguments by

• by reference
• by const-reference

Function arguments in C and C++

In C, we can pass arguments by value:

void myfn(int arg);

And by a pointer

void myfn(int* p);

In C++, we mainly pass arguments by value:

void myfn(int arg);

and by a const-reference:

void myfn(const MyClass& arg);

Built-in types are passed by value and complex types (classes) are usually passed by const-reference. Passing by const-reference avoids creating costly copies and makes the object a read-only object.

Are references pointers?

References are not pointers. They are a different kind of type. They are simply aliases, another name for something that is already there in memory. In C, we can declare a pointer-type function parameter and pass in the address of an existing object. In C++, an equivalent would be to declare a reference-type function parameter and pass in the object's name.

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