W3Schools
w3schools.com › c › c_typedef.php
C typedef
C Examples C Real-Life Examples C Exercises C Quiz C Code Challenges C Practice Problems C Compiler C Syllabus C Study Plan C Interview Q&A ... The typedef keyword lets you create a new name (an alias) for an existing type.
GeeksforGeeks
geeksforgeeks.org › c language › typedef-in-c
C typedef - GeeksforGeeks
July 23, 2025 - The typedef is a keyword that is used to provide existing data types with a new name. The C typedef keyword is used to redefine the name of already existing data types.
c - What is the use of typedef? - Stack Overflow
What is the use of typedef keyword in C ? When is it needed? More on stackoverflow.com
What exactly does this typedef line do?
However, I the syntax of typedef is typedef . The line of code in question doesn't seem to follow this question. It follows exactly the same syntax as a variable declaration, just with the keyword typedef out the front. So: char a[4]; means "declare a as an array of 4 characters", and: typedef char t[4]; means "define t as the type 'an array of 4 characters'". And yes, since it works just like a variable declaration, you can even define multiple types at once. For example: typedef char t4[4], t8[8], *tp, (*tpf)(void); would define: t4 to be the type 'an array of 4 characters`; t8 to be the type 'an array of 8 characters`; tp to be the type 'pointer to a character'; tpf to be the type 'pointer to a function that takes no arguments and returns a character'. So thinking of typedef as only permitting typedef is overly simplistic. (Fun fact: typedef has to be one of the "declaration specifiers" that go in front of the declarator list, but it need not be the first! Technically speaking, you could write it after the char type specifier instead — char typedef t[4]. But you'll confuse the heck out of anybody that looks at this line of code in the future... so please don't do that.) More on reddit.com
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August 7, 2022A new C++ back end for ocamlc
Finally, I can get some primes on my laptop · As a C++ enjoyer I can confirm this is some excellent idiomatic, readable C++ code More on news.ycombinator.com
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3 weeks agoWhat exactly does typedef do in C?
Answer: In C, the typedef keyword is used to create an alias for existing data types. It allows you to define a new name (or type) for a data type,... More on urbanpro.com
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April 15, 2025Videos
TutorialsPoint
tutorialspoint.com › cprogramming › c_typedef.htm
Typedef in C
The C programming language provides a keyword called typedef to set an alternate name to an existing data type. The typedef keyword in C is very useful in assigning a convenient alias to a built-in data type as well as any derived data type such as
Wikipedia
en.wikipedia.org › wiki › Typedef
typedef - Wikipedia
2 weeks ago - typedef is a reserved keyword in the programming languages C, C++, and Objective-C. It is used to create an additional name (alias) for another data type, but does not create a new type, except in the obscure case of a qualified typedef of an array type where the typedef qualifiers are transferred ...
AlphaCodingSkills
alphacodingskills.com › c › c-typedef.php
C Typedef - AlphaCodingSkills
typedef is a keyword in C language which is used to assign alternative name to existing datatype. It does not introduce a distinct type, it only establishes a synonym for an existing datatype.
Wideskills
wideskills.com › c-tutorial › c-typedef
C Typedef | Wideskills
typedef keyword is used in C programming language to create a different or new name/names for an already existing data type.
SkillVertex
skillvertex.com › blog › c-typedef
C Typedef
May 10, 2024 - The typedef keyword in C is used to give existing data types a new name. It’s essentially a way to redefine the names of existing data types. This is especially useful when the original names of data types are cumbersome to work with in your ...
C++ Core Guidelines
isocpp.github.io › CppCoreGuidelines › CppCoreGuidelines
C++ Core Guidelines
The C++ Core Guidelines are a set of tried-and-true guidelines, rules, and best practices about coding in C++
Top answer 1 of 8
71
typedef is for defining something as a type. For instance:
typedef struct {
int a;
int b;
} THINGY;
...defines THINGY as the given struct. That way, you can use it like this:
THINGY t;
...rather than:
struct _THINGY_STRUCT {
int a;
int b;
};
struct _THINGY_STRUCT t;
...which is a bit more verbose. typedefs can make some things dramatically clearer, specially pointers to functions.
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From wikipedia:
typedef is a keyword in the C and C++ programming languages. The purpose of typedef is to assign alternative names to existing types, most often those whose standard declaration is cumbersome, potentially confusing, or likely to vary from one implementation to another.
And:
K&R states that there are two reasons for using a typedef. First, it provides a means to make a program more portable. Instead of having to change a type everywhere it appears throughout the program's source files, only a single typedef statement needs to be changed. Second, a typedef can make a complex declaration easier to understand.
And an argument against:
He (Greg K.H.) argues that this practice not only unnecessarily obfuscates code, it can also cause programmers to accidentally misuse large structures thinking them to be simple types.
Reddit
reddit.com › r/c_programming › what exactly does this typedef line do?
r/C_Programming on Reddit: What exactly does this typedef line do?
August 7, 2022 -
I am reading some code and I came across the following strange line: typedef char MM_typecode[4]; . If I had to guess what it's doing, I would say that MM_typecode becomes an alias for "char array of size 4".
However, the syntax of typedef is typedef <old type> <new name for old type (alias) >. The line of code in question doesn't seem to follow this rule.
If I wanted to make MM_typecode as an alias for "char array of size 4", I would do typedef char[4] MM_typecode.
Top answer 1 of 4
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However, I the syntax of typedef is typedef . The line of code in question doesn't seem to follow this question. It follows exactly the same syntax as a variable declaration, just with the keyword typedef out the front. So: char a[4]; means "declare a as an array of 4 characters", and: typedef char t[4]; means "define t as the type 'an array of 4 characters'". And yes, since it works just like a variable declaration, you can even define multiple types at once. For example: typedef char t4[4], t8[8], *tp, (*tpf)(void); would define: t4 to be the type 'an array of 4 characters`; t8 to be the type 'an array of 8 characters`; tp to be the type 'pointer to a character'; tpf to be the type 'pointer to a function that takes no arguments and returns a character'. So thinking of typedef as only permitting typedef is overly simplistic. (Fun fact: typedef has to be one of the "declaration specifiers" that go in front of the declarator list, but it need not be the first! Technically speaking, you could write it after the char type specifier instead — char typedef t[4]. But you'll confuse the heck out of anybody that looks at this line of code in the future... so please don't do that.)
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The struct typedefs are interesting too. But not as crazy as function pointer typedefs.
Vardhaman
vardhaman.org › wp-content › uploads › 2021 › 03 › CP.pdf pdf
C PROGRAMMING Page 1 VARDHAMAN COLLEGE OF ENGINEERING (AUTONOMOUS)
const continue default do · double enum else extern · float for goto if · int long return register · signed short static sizeof · struct switch typedef union · unsigned void volatile while · Note: Keywords we cannot use it as a variable name, constant name etc.
Hacker News
news.ycombinator.com › item
A new C++ back end for ocamlc | Hacker News
3 weeks ago - Finally, I can get some primes on my laptop · As a C++ enjoyer I can confirm this is some excellent idiomatic, readable C++ code
Aticleworld
aticleworld.com › home › typedef in c language: 7 application you should know
typedef in C language: 7 application you should know - Aticleworld
January 15, 2020 - typedef in C is an important keyword that is used to define a new name for existing types, it does not introduce a new type. The typedef is the compiler directive mainly use with user-defined data types (structure, union or enum) to reduce their ...
Quora
quora.com › What-exactly-does-typedef-do-in-C
What exactly does typedef do in C? - Quora
Answer (1 of 16): As everyone said typedef is an alias name given to another type. [code]typedef int number; number x = 10; [/code]In the above example, I have given new name ‘number’ to the data type ‘int’ and I can use this new name where ever I need to use int. OK, that sounds not ...
UrbanPro
urbanpro.com › c language › learn c language
What exactly does typedef do in C? - UrbanPro
April 15, 2025 - The C typedef keyword is used to redefine the name of already existing data types.
Learn C
learnc.net › home › learn c programming › c typedef
C typedef
April 13, 2025 - For example: ... The scope of the ... scope of the new type is global if the new type is defined globally. First, the typedef keyword is used to make your code more portable....
cppreference.com
en.cppreference.com › cpp › language › typedef
typedef specifier - cppreference.com
May 11, 2025 - A typedef declaration may declare one or many identifiers on the same line (e.g. int and a pointer to int), it may declare array and function types, pointers and references, class types, etc.
Unstop
unstop.com › home › blog › typedef in c | usage with mulitple data types (+examples)
Typedef In C | Usage With Mulitple Data Types (+Examples)
May 15, 2024 - Typedef in C is a reserved keyword used to create an alias/ new name for existing data types. The primary purpose is to simplify complex type declarations in code.
Educative
educative.io › blog › how-to-use-the-typedef-struct-in-c
How to use the typedef struct in C
May 19, 2025 - C offers the typedef keyword to allow users to specify alternative simple and desired names for the primitive (e.g. int) and user-defined data types (e.g. struct). The typedef simplifies the use of complex data structures by allowing us to define ...
Go
go.dev › ref › spec
The Go Programming Language Specification - The Go Programming Language
A type definition creates a new, distinct type with the same underlying type and operations as the given type and binds an identifier, the type name, to it. TypeDef = identifier [ TypeParameters ] Type .