Programming languages - C Programming

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Lesson Description

Lession - #20 C Typedef

The C programming language provides a keyword called typedef, which you can use to give a type a new name. Following is an example to define a term BYTE for one-byte numbers −

typedef unsigned char BYTE;
After this type definition, the identifier BYTE can be used as an abbreviation for the type unsigned char, for example..

BYTE  b1, b2;
By convention, uppercase letters are used for these definitions to remind the user that the type name is really a symbolic abbreviation, but you can use lowercase, as follows −

typedef unsigned char byte;
You can use typedef to give a name to your user defined data types as well. For example, you can use typedef with structure to define a new data type and then use that data type to define structure variables directly as follows −

#include <stdio.h>
#include <string.h>
typedef struct Books {
   char title[50];
   char author[50];
   char subject[100];
   int book_id;
} Book;
int main( >
{ Book book; strcpy( book.title, "C Programming">
; strcpy( book.author, "Nuha Ali">
; strcpy( book.subject, "C Programming Tutorial">
; book.book_id = 6495407; printf( "Book title : %s\n", book.title>
; printf( "Book author : %s\n", book.author>
; printf( "Book subject : %s\n", book.subject>
; printf( "Book book_id : %d\n", book.book_id>
; return 0; }
When the above code is compiled and executed, it produces the following result −

Book  title : C Programming
Book  author : Nuha Ali
Book  subject : C Programming Tutorial
Book  book_id : 6495407