//
// Created by zing on 6/1/2020.
//
#include
using namespace std;
void define() {
//1ã€æŒ‡é’ˆçš„定义
int a = 10; //定义整型å˜é‡a
//指针定义è¯æ³•ï¼š æ•°æ®ç±»åž‹ * å˜é‡å ;
int *p;
//指针å˜é‡èµ‹å€¼
p = &a; //指针指å‘å˜é‡a的地å€
cout << &a << endl; //打å°æ•°æ®a的地å€
cout << p << endl; //打å°æŒ‡é’ˆå˜é‡p
//2ã€æŒ‡é’ˆçš„使用
//通过*æ“作指针å˜é‡æŒ‡å‘的内å˜
cout << "*p = " << *p << endl;
}
void space() {
int a = 10;
int *p;
p = &a; //指针指å‘æ•°æ®a的地å€
cout << *p << endl; //* 解引用
cout << sizeof(p) << endl;
cout << sizeof(char *) << endl;
cout << sizeof(float *) << endl;
cout << sizeof(double *) << endl;
}
void null_pointer() {
//指针å˜é‡p指å‘内å˜åœ°å€ç¼–å·ä¸º0的空间
int *p = NULL;
//访问空指针报错
//内å˜ç¼–å·0 ~255为系统å 用内å˜ï¼Œä¸å…许用户访问
cout << *p << endl;
}
void wild_pointer() {
//指针å˜é‡p指å‘内å˜åœ°å€ç¼–å·ä¸º0x1100的空间
int *p = (int *) 0x1100;
//访问野指针报错
cout << *p << endl;
}
void const_pointer() {
int a = 10;
int b = 10;
//const修饰的是指针，指针指å‘å¯ä»¥æ”¹ï¼ŒæŒ‡é’ˆæŒ‡å‘的值ä¸å¯ä»¥æ›´æ”¹
const int *p1 = &a;
int const *pp2 = &a;
p1 = &b; //æ£ç¡®
pp2 = &b; //æ£ç¡®
a = 20;
//*p1 = 100; //报错
//*pp2 = 1;
//const修饰的是常é‡ï¼ŒæŒ‡é’ˆæŒ‡å‘ä¸å¯ä»¥æ”¹ï¼ŒæŒ‡é’ˆæŒ‡å‘的值å¯ä»¥æ›´æ”¹
int *const p2 = &a;
//p2 = &b; //错误
*p2 = 100; //æ£ç¡®
cout << *p2 << endl;
//const既修饰指针åˆä¿®é¥°å¸¸é‡
const int *const p3 = &a;
//p3 = &b; //错误
//*p3 = 100; //错误
}
void array() {
int arr[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
int *p = arr; //指å‘数组的指针
cout << "ç¬¬ä¸€ä¸ªå…ƒç´ ï¼š " << arr[0] << endl;
cout << "æŒ‡é’ˆè®¿é—®ç¬¬ä¸€ä¸ªå…ƒç´ ï¼š " << *p << endl;
for (int i = 0; i < 10; i++) {
//利用指针é历数组
cout << *p << endl;
p++;
}
}
//å€¼ä¼ é€’
void swap1(int a, int b) {
int temp = a;
a = b;
b = temp;
}
//地å€ä¼ 递
void swap2(int *p1, int *p2) {
int temp = *p1;
*p1 = *p2;
*p2 = temp;
}
void function() {
int a = 10;
int b = 20;
swap1(a, b); // å€¼ä¼ é€’ä¸ä¼šæ”¹å˜å®žå‚
swap2(&a, &b); //地å€ä¼ 递会改å˜å®žå‚
cout << "a = " << a << endl;
cout << "b = " << b << endl;
}
//冒泡排åºå‡½æ•°
void bubbleSort(int *arr, int len) //int * arr 也å¯ä»¥å†™ä¸ºint arr[]
{
for (int i = 0; i < len - 1; i++) {
for (int j = 0; j < len - 1 - i; j++) {
if (arr[j] > arr[j + 1]) {
int temp = arr[j];
arr[j] = arr[j + 1];
arr[j + 1] = temp;
}
}
}
}
//打å°æ•°ç»„函数
void printArray(int arr[], int len) {
for (int i = 0; i < len; i++) {
cout << arr[i] << endl;
}
}
void sort() {
int arr[10] = {4, 3, 6, 9, 1, 2, 10, 8, 7, 5};
int len = sizeof(arr) / sizeof(int);
bubbleSort(arr, len);
printArray(arr, len);
}
int main(int argc, char *argv[]) {
define();
space();
//null_pointer();
//wild_pointer();
const_pointer();
array();
function();
sort();
return 0;
}