C Language Fifth day note January 18, 2016 (Monday) a.m.

1. Functions (supplement, understanding)

function parameters have default values and must have default values from right to left

Example: int foo (int a,int b=1,int c=2) {

return a+b+c;} Legal

int foo (int a=1,int b,int c=2) {

return a+b+c;} Not legal

Inline functions: Use the inline keyword when declaring (and not necessarily all compilers support inline functions).

inline function: Before compiling, the compiler replaces the function call statement with the function body, eliminating the "Look for function implementation" time when executing. It's a space-time-changing operation.

Normal function: When the program runs, the compiler will find the function body according to the function name

Function overloading: (c + + features)

Function names are the same, parameter lists are different. The parameter list is divided into two cases, the number of parameters is different, the parameter type is different.

2. Pointers:

What is the 2.1 pointer? The pointer is the address.

Pointer variable: The address number is stored

Integer variables: integers are stored

2.2 Declaration Pointers

Declaring an integer variable: int A;

Declare pointer variable: base type * variable name;

Example: int* p; double** Q;

Base type: The variable type "point" of the pointer int* p;

P The base type of "point" is int type Q "point" double* type

"Point": Char achar= ' G ';

Char* p; The p=&achar;//pointer variable p Stores the address number of the Achar variable, which is called the pointer p to Achar.

3. Use of pointers

int A;

int* P=&a

int** qq=&p//Two-level pointer "point" level pointer

Print Address:%p

Print Length:%lu sizeof ()

Initialization

The variable p is an lvalue indicating that the space P is the value of the right value representing the space

Example: int A; int* Q; q=&a; Variable q initialization, so the left value is the variable name Q

int** QQ; qq=&q;

*：

int* (data type *): * indicates that P is a pointer variable.

*p: Address character

int a=10;

int* P =&a;

printf ("%d%d\n", a,*p);//10 10

*p=20; *p⇔* (&a) ⇔a

printf ("%d%d\n", a,*p);//20 20

int* *q=&p;

printf ("%d%d%d\n", a,*p,**q);//20 20 20

q=&p=& (&a); two-time value

return 0;

Null pointer: A null-valued pointer

C Language Fifth day note January 18, 2016 (Monday) a.m.