Difference Between `struct Foo` and `typedef struct` in C++

By the end of this page, you will understand how struct names work in C++, what typedef struct { ... } Foo; actually creates, and why the first form is usually preferred in modern C++ code. You will also see how this differs from C-style usage and how developers typically write type aliases today.

In C++, struct defines a type. Unlike C, the name of the struct becomes a normal type name immediately.

That means this is enough:

struct Foo {
    int value;
};

Foo x;

You do not need typedef just to use Foo as a type name.

Now compare that with:

typedef struct {
    int value;
} Foo;

This creates an anonymous struct type and then gives that type the alias Foo using typedef.

So the main difference is:

• struct Foo { ... };
  • defines a struct named Foo
• typedef struct { ... } Foo;
  • defines an unnamed struct and creates a typedef name Foo for it

In C++, both can often be used similarly afterward:

Think of a type like a person in a contact list.

• struct Foo { ... }; means the person is officially named Foo.
• typedef struct { ... } Foo; means the person has no original name, but you saved them in your phone as Foo.

In everyday use, you can still call them Foo, but internally the first one has a real declared type name, while the second is an unnamed type with an alias attached to it.

In C++, giving the type a real name directly is usually the cleaner choice.

Core syntax

Named struct in C++

struct Foo {
    int value;
};

Foo a;

This defines a type named Foo.

Anonymous struct with a typedef alias

typedef struct {
    int value;
} Foo;

Foo a;

This defines an unnamed struct type and creates the alias Foo.

Example showing the practical difference

struct Person {
    std::string name;
    int age;
};

typedef struct {
    std::string title;
    double price;
} Product;

Person p{"Maya", 28};
Product item{"Notebook", 4.99};

Here:

• Person is the actual name of the type
• Product is a typedef name for an unnamed type

Modern C++ alias style

Consider this example:

struct Foo {
    int value;
};

typedef struct {
    int value;
} Bar;

int main() {
    Foo a{10};
    Bar b{20};
}

What happens step by step

1. struct Foo { int value; };

   • A struct type is created.
   • Its name is Foo.

2. typedef struct { int value; } Bar;

   • Another struct type is created.
   • This struct has no direct name.
   • Bar becomes a typedef name for that unnamed type.

3. Foo a{10};

   • A variable a is created using the named type Foo.

4. Bar b{20};

   • A variable is created using the typedef alias .

When you see struct Foo { ... };

This is the normal style in modern C++ for:

• data models
• configuration objects
• simple value types
• small helper types
• public API types

Example:

struct Config {
    std::string host;
    int port;
    bool debug;
};

When you might see typedef struct { ... } Foo;

This is common in:

• old C code
• C headers written for C compatibility
• codebases that started in C and later included C++
• cross-language or legacy APIs

Example from C-style code:

typedef struct {
    int x;
    int y;
} Point;

In C, this pattern is useful because plain struct Foo and Foo are not automatically the same thing. In C++, that extra typedef is usually unnecessary.

In real C++ projects, developers usually prefer the named form:

struct User {
    std::string email;
    bool active;
};

Common reasons:

• easier to read
• easier to forward declare
• easier to document
• fits modern C++ style

Common patterns in codebases

1. Public data structures

struct Request {
    std::string path;
    std::string method;
};

2. Configuration objects

struct DatabaseOptions {
    std::string host;
    int port;
};

3. Type aliases with using

If a shorter or more meaningful alias is needed:

struct DatabaseOptions {
    std::string host;
    int port;
};

using DbOptions = DatabaseOptions;

4. Forward declarations

A named struct can be declared before its full definition:

1. Assuming C and C++ treat struct names the same way

Beginners often learn a C-style pattern and use it in C++ without knowing why.

C++

struct Foo {
    int x;
};

Foo a; // valid

In C

struct Foo {
    int x;
};

struct Foo a; // needed unless typedef is used

In C++, the struct name is already a usable type name.

2. Thinking typedef struct { ... } Foo; creates a struct named Foo

It does not.

typedef struct {
    int x;
} Foo;

Here, the struct itself is unnamed. Foo is a typedef alias.

3. Using old C-style syntax in modern C++ without a reason

This is valid C++, but usually not the clearest style:

Quick rules

• In C++, struct Foo { ... }; already creates a usable type name: Foo
• typedef struct { ... } Foo; creates an anonymous struct plus alias Foo
• In modern C++, prefer named structs directly
• If you need an alias, prefer using over typedef

Common forms

struct Foo {
    int x;
};

typedef struct {
    int x;
} Foo;

using Alias = Foo;

Best practice

Prefer:

struct Foo {
    int x;
};

Why

• clearer intent
• easier forward declarations
• more idiomatic C++
• avoids old C-style noise

Edge case

Is typedef struct needed in C++?

No. In C++, a struct name is already a normal type name.

Are the two forms exactly equivalent?

Not exactly. They often behave similarly when creating variables, but one defines a named type and the other defines an unnamed type with an alias.

Which style should I use in modern C++?

Use struct Foo { ... }; in most cases. It is the clearer and more idiomatic form.

Why do I still see typedef struct in some code?

Usually because the code is old, written in C style, or intended to be compatible with C.

Can an anonymous struct typedef be forward-declared?

Not in the same simple way as a named struct, because the struct itself has no name.

Should I use typedef or using in modern C++?

Prefer using for new aliases. It is clearer and more flexible, especially with templates.

Is struct different from class here?

Not for naming. The main difference between struct and class in C++ is default access level, not whether the type is usable by name.

• struct in C++ — Related because this question is about how structs define types.
• typedef in C++ — Related because one form uses typedef to create an alias.
• using type aliases — Related because using is the modern replacement for many typedef cases.
• struct vs class in C++ — Related because beginners often compare these keywords together.
• Forward declarations — Related because named structs can be forward-declared more easily.
• C vs C++ type naming — Related because the main confusion comes from differences between the two languages.
• Anonymous types — Related because typedef struct { ... } Foo; creates an unnamed struct type.