Introduction to C Language Learning (9) typedef keywords

Introduction to C Language Learning (9) typedef keywords

Keyword: typedef

Usage: define a new name (alias) for various data types)

Typedef and basic data types

Typedef int Integer; Integer a = 8;

You can also create another alias Based on the alias.

Typedef Integer MyInteger; MyInteger a = 8;

The original data type can also be used normally.

Typedef and pointer

Typedef char * String; String str = "jackie ";

Typedef andStruct

TypedefstructPerson Per; // you do not need to include the struct keyword when defining the struct variable.

Per p; p. name = "xyz ";

Define and take the alias:

Typedefstruct Student // The struct name Student can be omitted.

{

Int age;

} Stu;

Void processStudent ()

{

Stu student = {18 };

Student. age = 19;

}

Typedef and pointStructPointer

Typedef struct

{

Int age;

} Stu;

Stu stu = {20 };

Typedef Stu * S; // the alias S for the pointer to the struct.

S s = & stu;

Typedef struct LNode

{

Int data;

Struct LNode * next;

} LinkList, * SList;

Int main (int argc, const char * argv [])

{

LinkList l = {1, NULL };

LinkList ll = {2, NULL };

L. next = & ll;

Printf ("% d,", l. next-> data );

SList sl = & ll;

If (sl-> next! = NULL)

Printf ("% d,", sl-> data );

Return 0;

}

Typedef andEnumeration type

Typedef enum

{

...

} Season;

// Similar to struct

Typedef andPointer to function

Int sum (int a, int B)

{

Return a + B;

}

Void main ()

{

Typedef int (* P) (int a, int B );

P p = sum;

Int result = (* p) (3, 5 );

Return 0;

}

Typedef and # define

Typedef char * String;

String s = "abc"

# Define String char *;

String s = "abc"; // The effect is the same

To use this method:

String s1, s2; // Replace the first one with char * s1, char * s2;

String s3, s4; // replace char * s3, s4; <=> char * s3, char s4;