C Language Grammar Note – Advanced usage pointer array pointer pointer to a two-dimensional array pointer structure pointer list | It house. com

Original: C language Grammar note – Advanced usage pointer array pointer pointer to two-dimensional array pointer structure pointer list | It house. com

C Language Grammar Note – Advanced usage pointer array pointer pointer to a two-dimensional array pointer structure pointer list | It house. com

C language Grammar Note – Advanced usage pointer array pointer pointer to two-dimensional array pointer structure pointer list
This article was posted 315 days ago by arthinking ⁄itzhai.com Original article ⁄c language ⁄ comments 3⁄ be onlookers 1,775 views+
 

Array of pointers: In an array, if its elements are all data of pointer type, then this array is called an array of pointers.

Definition: type name * array name [array length];

Char *suit[3] = {"First", "second", "Third"}; pointer to pointer:

If one variable holds the address of another pointer variable, the pointer variable is called a pointer variable that points to the pointer data, called a multilevel pointer, or a pointer to a pointer.

Definition: Type identifier * * pointer variable name;

Accessing another variable with a pointer variable is "indirect access", where the address of a target variable is stored in a pointer variable, which is "single-level addressing".

For array suit, because the array name itself represents the address, you can create a level two pointer directly:

char **p;p = suit;

#include <stdio.h>void main () {int a[5] = {1,3,5,7,9};int *num[5],i;int **p;for (i=0;i<5;i++) {num[i] = &a[i] ;} p = num;for (i=0;i<5;i++) {printf ("%d", **p);p + +;} printf ("\ n");}

Pointer to a two-dimensional array:

Address of the two-dimensional array:

A=a[0][0]=a[0] a+1=a[1] a[0]+1=a[0][1]

A is a row pointer, *a is a column pointer, **a represents the value of a[0][0], *a represents the address of a[0]. A[1]+2 equivalent to * (a+1) +2

Before the line pointer is preceded by a * to convert to a column pointer, if a and a+1 are row pointers, then *a and * (a+1) are column pointers.

Pointer variable to array element

#include <stdio.h>void main () {int a[3][4] = {1,2,3,4,5,6,7,8,9,10,11,12}int *p;for (p = a[0]; p<a[0]+12; p++) {if ((p-a[0])%4 = = 0) printf ("\ n");p rintf ("%4d", *p);}}

Pointer variable to a one-dimensional array consisting of M elements

This pointer makes p+1 not point to a[0][1], but instead points to the increment of a[1],p in the length of an array, which is called a row pointer.

Data type (* pointer variable name) [N];

int a[4][3], (*P) [3];

Functions that return pointers

function type * function name ([formal parameter type declaration table]) {function Body}

Pointers to functions

A general definition of a pointer to a function:

Data type (* pointer variable name) (parameter type list)

Call Mode:

(* pointer variable name) (actual parameter list)

Int (*functionpointer) (int a); Functionpointer = func;   Func is the function name (*functionpointer) (100);

Main function with parameters

void Main (int argc, char *argv[]) {function Body}

ARGC indicates the number of command-line arguments, argv represents the parameter array

Pointers to struct bodies

struct Student *p;struct Student stu;p = &stu;//Three ways to get child elements: stu.name; (*p) .name;p->name;  Methods of pointers

Pointer to an array of struct bodies

A pointer to a struct array is actually similar to a pointer to a two-dimensional array previously defined, and can be understood as a row pointer to an array of two-bit addresses.

Dynamic memory allocation:

void *malloc (unsigned int size);

Newptr = malloc (sizeof (struct node));

void free (void *p)

Linked list structure:

#include <stdio.h> #define NULL 0#define LEN sizeof (struct student)/* Defines the length of the node */#define node struct studentstruct stu Dent{char no[5];float score;struct student *next;}; struct student *create (void); void printlist (struct student *head); Node * INSERT (node *head, node *new, int i); Node * dellist (node *head,char no[]); void main () {struct student *a;struct student test1={"ABC", 1.0,NULL};STRUCT Student * Test2;a = Create ();p rintf ("Insert new node\n"), test2 = &test1;a = insert (a,test2,2);p rintlist (a);p rintf ("delete Node\n "), a = Dellist (A," 2 ");p rintlist (a); Getch ();} /* Create a single-linked list with a head node that returns the head pointer of the single-linked list */struct student *create (void) {struct student *head = NULL, *new1, *tail;int count = 0;for (;;)  {New1 = (struct student *) malloc (LEN); /* Apply for a new node space */printf ("Input the number of student no.%d (5bytes):", Count + 1), scanf ("%5s", new1->no); if (strcmp (new1-   >no, "*") = = 0)/* Here does not need to add the address symbol, because no represents the first address of the array */{free (NEW1);  /* Release the last requested node space */break; /* End For statement */}printf ("Input The score of the student no.%d:", Count +1); scanf ("%f", &new1->score); count++;/* inserts a new node into the end of the list and sets a new tail pointer */if (count = = 1) {head = New1;  /* is the first node, the head pointer */} ELSETAIL-&GT;NEXT = New1;    /* is not the first node, insert the new node into the end of the list */tail = New1; /* Set new tail node */}/* the pointer field for the new node is empty */new1->next = Null;return (head);} /* Output list */void printlist (struct student *head) {struct Student *p;p = head;if (head = = NULL) {printf ("List is empty!!! \ n ");} else {while (p!=null) {printf ("%5s%4.1f\n", p->no,p->score);p = P->next;}}} /* Insert List node */node * INSERT (node *head, node *new, int i) {node *pointer;/* inserts a new node into the list */if (head = = NULL) {head = new; New->nex t = NULL;} else {if (i = = 0) {new, next = Head;head = new;} else {pointer = head;/* finds the first node of the single-linked list (pointer points to it) */for (;p ointer! = NULL & amp;& i > 1; pointer = pointer->next,i--); if (pointer = = NULL) printf ("Out of the Range,can ' t insert new node!\n"); else {/* General Poin ter points to the first node */new next = Pointer->next;pointer->next = new;}} return (head);}    /* Delete List */node * dellist (node *head,char no[]) {node *front; /*front means to delete the knotPoint of the previous node */node *cursor; /*cursor represents the node */if (head = NULL) that is currently being deleted {/* empty list */printf ("\nlist is empty\n"), return (head); if (strcmp (head->no,no = = 0)) {/* the node to be deleted is the header node */front = Head;head = Head->next;free (front);} else {/* Non header node */front = Head;cursor = head->next;/* moves through the loop to the location of the node to be deleted */while (cursor! = NULL && strcmp (cursor->no,no)! = 0) {front = C Ursor;cursor = cursor->next;} if (cursor! = NULL) {/* Find the node that needs to be deleted for deletion */front->next = Cursor->next;free (front);} else {printf ("%5s have not been fou nd! ", *no);}} return (head);}

In addition to the article has special instructions, are it house original articles, reproduced please link the form to indicate the source.

This article link: http://www.itzhai.com/ C-language-syntax-notes-advanced-usage-of-two-dimensional-array-of-pointers-to-a-pointer-list-pointer-array-pointer-struc ture.html keywords: c language, pointers, linked list

C Language Grammar Note – Advanced usage pointer array pointer pointer to a two-dimensional array pointer structure pointer list | It house. com