{"id":83474,"date":"2021-08-11T09:00:31","date_gmt":"2021-08-11T03:30:31","guid":{"rendered":"https:\/\/techvidvan.com\/tutorials\/?p=83474"},"modified":"2021-08-11T09:00:31","modified_gmt":"2021-08-11T03:30:31","slug":"c-typedef-with-examples","status":"publish","type":"post","link":"https:\/\/techvidvan.com\/tutorials\/c-typedef-with-examples\/","title":{"rendered":"C Typedef with Examples"},"content":{"rendered":"

The C programming language supports various keywords and data types. In C, you can also create your own data type. Typedef is a predefined keyword. This keyword helps in creating a user defined name for an existing data type.<\/p>\n

What is the typedef keyword in C?<\/h3>\n

As discussed, it is a predefined keyword. With the help of this keyword, you can give a meaningful name to an existing variable in your C program. To put it short, you can replace the name of the existing data type with the name which you have provided. It works similarly when we define aliases for the commands.<\/p>\n

Working of C typedef<\/h3>\n

To implement the typedef keyword successfully, you will have to give a meaningful name to an existing data type in the program code. Then the compiler replaces the existing data type with the name that you have provided for the entire application.<\/p>\n

Syntax1:- Using typedef keyword in C<\/strong><\/p>\n

typedef <existing data type or keyword> <user given name for the datatype or keyword><\/pre>\n
Syntax2:- Working of typedef<\/strong><\/p>\n
typedef struct\n{\n    data_type member1;\n    data_type member2;\n    data_type member3;\n}type_name;\n<\/pre>\n
Example:- typedef keyword in C<\/strong><\/p>\n
typedef unsigned int length;<\/pre>\n
In the above example, we have declared an unsigned int type variable length with the help of typedef keyword. Now we can create unsigned int type variables with length like below:-<\/p>\n
length i,j;<\/pre>\n
Suppose, you have to declare an unsigned int datatype at various locations in your program code. It will be lazy work. But the typedef keyword will make your work easy.<\/p>\n
Basic Example of C typedef keyword<\/strong><\/p>\n
#include<stdio.h>\ntypedef int ainT; \/\/declared a new variable of int data type!\nint main ()\n{\n  printf(\"TechVidvan Tutorial: Example of typedef keyword!\\n\\n\");\n  int a=10;\n  ainT b=50,c;\n  c = a + b;\n  printf (\"Sum is: %d\", c);\n  return 0;\n}\n<\/pre>\n
Output:-<\/strong><\/p>\n
\n
TechVidvan Tutorial: Example of typedef keyword!<\/p>\n
Sum is: 60<\/p>\n<\/div>\n
Example of typedef in C<\/h4>\n
Suppose, you want to create a record of a student which includes student details such as name, id, subjects, marks, phone number etc. then you can do all this by defining a structure. It helps you in increasing the readability of the program code.<\/p>\n
#include<stdio.h>\ntypedef struct details\n{\nint age;\nint id;\n}student;\nint main( )\n{\nstudent s1;\nprintf(\"TechVidvan Tutorial: Example of typedef in C!\\n\\n\");\ns1.age = 21;\ns1.id = 3;\nprintf(\"AGe of the student is: %d\\n\", s1.age);\nprintf(\"Id of the student is: %d\\n\", s1.id);\nreturn 0;\n}<\/pre>\n
Output:-<\/strong><\/p>\n
\n
TechVidvan Tutorial: Example of typedef in C!<\/p>\n
AGe of the student is: 21
\nId of the student is: 3<\/p>\n<\/div>\n
C typedef struct<\/h3>\n
You can also use the typedef keyword with structures in C. With typedef, create a new data type and then use that to define structure variables.<\/p>\n
Example:- Using typedef with structures<\/strong><\/p>\n
typedef struct employee\n{  \nint salary;  \nint id;  \n}emp;\nemp e1,e2;<\/pre>\n
Example:- typedef with structures<\/strong><\/p>\n
#include <stdio.h>\ntypedef struct employee\n{  \nint salary;  \nint id;  \n}emp;  \nint main()  \n{  \nemp e1,e2;  \ne1.salary = 14000;\ne1.id = 1;\ne2.salary = 12000;\ne2.id = 2;\nprintf(\"TechVidvan Tutorial: typedef using struct!\");\nprintf(\"Salary of the first employee is : %d\\n\", e1.salary);\nprintf(\"ID of the first employee is : %d\\n\", e1.id);\nprintf(\"Salary of the second employee is : %d\\n\", e2.salary);\nprintf(\"ID of the second employee is : %d\\n\", e2.id);\nreturn 0;  \n}\n<\/pre>\n
Output:-<\/strong><\/p>\n
TechVidvan Tutorial: typedef using struct!Salary of the first employee is : 14000
\nID of the first employee is : 1
\nSalary of the second employee is : 12000
\nID of the second employee is : 2<\/div>\n
In the above example, we have declared variable emp of type struct employee. We can create variables using the emp variable of type struct employee. It helps in reducing the complexity of the code.<\/p>\n
How to use typedef in C?<\/h3>\n
In C, you can make use of the typedef keyword. It is mainly used to give meaningful names to the existing data type. Below, we have declared a real_int variable with typedef keyword.<\/p>\n
Example:- typedef keyword<\/strong><\/p>\n
#include<stdio.h>\nint main()\n{\nprintf(\"TechVidvan Tutorial: How to use typedef in C!\\n\\n\");\ntypedef real_int;\nreal_int num = 213;\nprintf(\"Number is: %d\\n\",num);\nreturn 0;\n}\n<\/pre>\n
Output:-<\/strong><\/p>\n
\n
TechVidvan Tutorial: How to use typedef in C!<\/p>\n
Number is: 213<\/p>\n<\/div>\n
C typedef with pointers<\/h3>\n
You can also use the typedef keyword with pointers.<\/p>\n
Example:- using typedef with pointers<\/strong><\/p>\n
typedef int* point;\npoint a,b;<\/pre>\n
In the above example, we have declared variable point of type *int. With that, we can create variables of type *int using the point variable.<\/p>\n
Example:- typedef with pointers<\/strong><\/p>\n
#include <stdio.h>\ntypedef int* point;\nint main(){\n  point a1;\n  a1 = 40;\n  printf(\"TechVidvan Tutorial: typedef using pointers!\\n\");\n  printf(\"Value is: %d\",a1);\n  return 0;\n}\n<\/pre>\n
Output:-<\/strong><\/p>\n
TechVidvan Tutorial: typedef using pointers!
\nValue is: 40<\/div>\n
In the above example, a1 is the variable of type *int.<\/p>\n
typedef and #define<\/h3>\n
#define directive works similar to the typedef keyword. #define directive is also used to define various data types like typedef keyword.<\/p>\n
    \n
  • #define directive is processed by the preprocessor and the typedef keyword is processed by the compiler.<\/li>\n
  • You have to put a semicolon at the end of a typedef keyword. But in #define, you don\u2019t have to.<\/li>\n
  • typedef is used for giving a new name to the existing data type. And #define is a directive which is used to give an alias for values like 1 as ONE, 3.14 as PI.<\/li>\n<\/ul>\n
    Example:- #define<\/strong><\/p>\n
    #include <stdio.h>\n#define SIDE  5\nint main( ) {\n  int area;\n  area = SIDE*SIDE;\n   printf(\"TechVidvan Tutorial: #define directive!\\n\");\n   printf(\"Area of square is: %d\",area);\n   return 0;\n}\n<\/pre>\n
    Output:-<\/strong><\/p>\n
    TechVidvan Tutorial: #define directive!
    \nArea of square is: 25<\/div>\n
    Example:- typedef<\/strong><\/p>\n
    #include <stdio.h>\ntypedef char c;\nint main()\n{\n  c c1;\n  c1 = 'T';\n  printf(\"Printing character: %c\", c1);\n  return 0;\n}<\/pre>\n
    Output:-<\/strong><\/p>\n
    Printing character: T<\/div>\n
    Below are some examples on how to use the typedef struct<\/strong>.<\/p>\n
    Example of Variable declaration without using typedef:-<\/strong><\/p>\n
    #include<stdio.h>\nstruct value{\n  int a;\n};\nint main() {\n  struct value i;\n  i.a=5;\n  printf(\"Value is: %d\\n\", i.a);\n  return 0;\n}<\/pre>\n
    Output:-<\/strong><\/p>\n
    Value is: 5<\/div>\n
    Difference between typedef and #define:-<\/h3>\n\n\n\n\n\n\n\n
    typedef<\/b><\/td>\n#define<\/b><\/td>\n<\/tr>\n
    It is compiler based.<\/span><\/td>\nIt is preprocessor based.<\/span><\/td>\n<\/tr>\n
    You have to put a semicolon at the end of the typedef keyword.<\/span><\/td>\nIn #define directive, you don\u2019t have to put a semicolon.<\/span><\/td>\n<\/tr>\n
    It is used for giving new names to data types only.<\/span><\/td>\n #define is a directive which is used to give an alias for values like 1 as ONE, 3.14 as PI.<\/span><\/td>\n<\/tr>\n
    Describes the actual definition of the new data type.<\/span><\/td>\nSimply copy and paste the definition values.<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
    Using typedef keyword<\/h3>\n
    You don\u2019t have to type struct keyword again and again in every declaration of variables.<\/p>\n
    Method One:-<\/strong><\/p>\n
    #include<stdio.h>\nstruct value{\n  int a;\n};\ntypedef struct value val;\nint main() {\n  val i;\n  i.a = 63;\n  printf(\"Value is: %d\\n\", i.a);\n  return 0;\n}<\/pre>\n
    Output:-<\/strong><\/p>\n
    Value is: 63<\/div>\n
    Method Two:-<\/strong><\/p>\n
    #include<stdio.h>\ntypedef struct value{\n  int i;\n}val;\nint main() {\n  val a;\n  a.i = 36;\n  printf(\"Value is: %d\\n\", a.i);\n  return 0;\n}<\/pre>\n
    Output:-<\/strong><\/p>\n
    Value is: 36<\/div>\n
    Application of typedef<\/h3>\n
    The typedef keyword is used to give a meaningful name to the existing data type.<\/p>\n
    Use of typedef with structures:-<\/strong><\/p>\n
    typedef struct\n{\ndata_type variable1;\ndata_type variable2;\n}variable_name;\n<\/pre>\n
    With that variale_name, you can declare variables of structure type like below:-<\/p>\n
    variable_name a,b;<\/pre>\n
    Example:- typedef unsigned char<\/strong><\/p>\n
    #include <stdio.h>\ntypedef unsigned char CHAR;\nint main()\n{\nCHAR letter1='T';\nCHAR letter2='e';\nCHAR letter3='c';\nCHAR letter4='h';\nCHAR letter5='V';\nCHAR letter6='i';\nCHAR letter7='d';\nCHAR letter8='v';\nCHAR letter9='a';\nCHAR letter10='n';\nprintf(\"TechVidvan Tutorial: typedef with unsigned char!\\n\\n\");\nprintf(\"Created word with alphabets: %c%c%c%c%c%c%c%c%c%c\",letter1,letter2,letter3,letter4,letter5,letter6,letter7,letter8,letter9,letter10);\nreturn 0;\n}<\/pre>\n
    Output:-<\/strong><\/p>\n
    \n
    TechVidvan Tutorial: typedef with unsigned char!Created word with alphabets: TechVidvan<\/p>\n<\/div>\n
    C Typedef using an array<\/h3>\n
    You can also use the typedef keyword with an array.<\/p>\n
    Example:-<\/strong><\/p>\n
    typedef int arr[10];<\/pre>\n
    arr is a variable of int data type. With that, you can also declare variables as much as you can.<\/p>\n
    For example:-<\/strong><\/p>\n
    arr i,j,k;<\/pre>\n
    Example:- typedef with an array<\/strong><\/p>\n
    #include<stdio.h>\ntypedef int arr[5];\n\nint main()\n{\n  int a;\n  arr i = {14,2,3,54,3};\n  printf(\"TechVidvan Tutorial: typedef using array!\\n\");\n  for(a = 0; a < 5; a++)\n  {\n    \tprintf(\"Element of %d is: %d\\n\",a ,i[a]);\n  }\n  return 0;\n}<\/pre>\n
    Output:-<\/strong><\/p>\n
    TechVidvan Tutorial: typedef using array!
    \nElement of 0 is: 14
    \nElement of 1 is: 2
    \nElement of 2 is: 3
    \nElement of 3 is: 54
    \nElement of 4 is: 3<\/div>\n
    Summary:-<\/h3>\n
    typedef is a predefined keyword. You can replace the name of the existing data type with the name which you have provided. This keyword helps in creating a user-defined name for an existing data type. You can also use the typedef keyword with structures, pointers, arrays etc.<\/p>\n","protected":false},"excerpt":{"rendered":"
    The C programming language supports various keywords and data types. In C, you can also create your own data type. Typedef is a predefined keyword. This keyword helps in creating a user defined name...<\/p>\n","protected":false},"author":1,"featured_media":83499,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3510],"tags":[4019,4020,4021,4022,4023,4024],"class_list":["post-83474","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-c-programming","tag-application-of-typedef","tag-c-typedef","tag-c-typedef-struct","tag-c-typedef-with-pointers","tag-difference-between-typedef-and-define","tag-typedef-using-an-array"],"yoast_head":"\nC Typedef with Examples - TechVidvan<\/title>\n<meta name=\"description\" content=\"Learn about C typedef with examples. 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