C语言基础 - 实现动态数组并增加内存管理

时间:2023-08-27 09:11:38

用C语言实现一个动态数组,并对外暴露出对数组的增、删、改、查函数

(可以存储任意类型的元素并实现内存管理)

这里我的编译器就是xcode

分析:

模拟存放 一个 People类 有2个属性 字符串类型:姓名 整型:年龄

array 结构体 应当有 数组长度:length 空间:capacity 存储对象:value(任意类型)

构造一个任意对象类.拥有retainCount属性.为内存计数器

使用一次retainCount+1,当retainCount为0时 释放该对象指向的内存

贴出部分代码

//  Object.h
#ifndef Object_h
#define Object_h
#include <stdio>
//定义结构体
typedef struct Object{
int retainCount;
}Object;
//宏定义方法 方便书写
#define OBJECTRETAIN(obj) objectRetain((Object*)obj)
#define OBJECTRELEASE(obj) objectRelease((Object*)obj)
#define GETRETAINCOUNT(obj) getRetainCount((Object*)obj)
void objectRetain(Object *obj);
void objectRelease(Object *obj);
int getRetainCount(Object *obj);
#endif /* Object_h */
//  Object.c
#include "Object.h"
#include <stdlib>
void objectRetain(Object *obj) { obj->retainCount ++;
// printf("retain计数+1 = %d\n",obj->retainCount); } void objectRelease(Object *obj) {
obj->retainCount --;
if (obj->retainCount <= 0) {
free(obj);
}
// printf("retain计数-1 = %d\n",obj->retainCount); }
//获得当前计数
int getRetainCount(Object *obj) {
return obj->retainCount;
}

下面开始封装.

首先是对原始数据的封装.

    1. 将char* 字符串类型 封装成String
//  String.h
#ifndef String_h
#define String_h
#include <stdio>
typedef struct String{
int retainCount;
char *value;
}String;
String* newString(char* value);
char* getStringValue(String* ins);
#endif /* String_h */
//  String.c
#include "String.h"
#include <stdlib>
#include "Object.h" String* newString(char* value){
String *str = malloc(sizeof(String));
OBJECTRETAIN(str);
str->value = value;
return str; }
char* getStringValue(String* ins){
return ins->value;
}
  • 2.将年龄的类型int封装成Interger
//  Integer.h

#ifndef Integer_h
#define Integer_h #include <stdio> typedef struct Integer{
int retainCount;
int value; }Integer; Integer* newInteger(int value);
int getIntegerValue(Integer* ins);
#endif /* Integer_h */
//  Integer.c

#include "Integer.h"
#include <stdlib>
#include "Object.h" Integer *newInteger(int value) {
Integer *new = malloc(sizeof(Integer));
OBJECTRETAIN(new);
new->value = value;
return new;
} int getIntegerValue(Integer* ins) {
return ins->value;
}
  • 3.定义数组中存放的类 包含 name 和 age 属性
//  People.h

#ifndef People_h
#define People_h #include <stdio>
#include "Integer.h"
#include "String.h" typedef struct People{
int retainCount;
String* name;
Integer* age; }People; People* newPeople(String *name,Integer *age);
String* getName(People* people);
Integer* getAge(People* people);
#endif /* People_h */
//  People.c

#include "People.h"
#include <stdlib>
#include "Object.h" People* newPeople(String *name,Integer *age){
People *newP = malloc(sizeof(People));
OBJECTRETAIN(newP);
newP->age = age;
newP->name = name;
return newP;
}
String* getName(People* people){
return people->name;
}
Integer* getAge(People* people){
return people->age;
}
  • 4.准备工作都做完 ,下面我们来实现数组Array
//  Array.h

#ifndef Array_h
#define Array_h #include <stdio>
#include "People.h"
#include "Object.h"
typedef Object* AnyObject; typedef struct Array{
int length;
int capacity;
AnyObject *value; }Array; Array* newArray(); //增加数组元素
void addElement(Array *array,AnyObject value); //删除
Array* removeIndexAt(Array *arry,int index); //插入
Array* insertIndexAt(Array *array,AnyObject value,int index); //查找
AnyObject getValueIndexAt(Array *array,int index); //获取数组长度
int getArrayLength(Array *array); //销毁
void destroyArray(Array *array); //打印
void printArray(Array *arr); #endif /* Array_h */
//  Array.c

#include "Array.h"
#include <string>
#include <stdlib>
#include <assert> //分配空间
static AnyObject* allocMemoryByCapacity(Array *arr){
return malloc(sizeof(AnyObject) * arr->capacity);
} //创建数组
Array* newArray(){
Array *arr = malloc(sizeof(Array));
arr->length = 0;
arr->capacity = 32;
arr->value = allocMemoryByCapacity(arr);
return arr;
} //获取数组长度
int getArrayLength(Array *array){
return array->length;
} //增加元素
void addElement(Array *array,AnyObject value){
if (array->length >= array->capacity) {
array->capacity *= 2;
AnyObject *oldValue = array->value;
memcpy(array->value, oldValue, array->length*sizeof(AnyObject));
free(oldValue);
}
OBJECTRETAIN(value);
array->value[array->length] = value;
array->length++;
} //删除元素
Array* removeIndexAt(Array *arry,int index){
assert(index >= 0 && index < arry>length); //断言 防止越界 OBJECTRELEASE(getValueIndexAt(arry, index)); arry->length -- ;
for (int i = index-1; i < arry>length; i++) {
arry->value[i] = arry->value[i+1];
}
return arry;
} //在指定位置增加元素
Array* insertIndexAt(Array *array,AnyObject value,int index){
if (array->length >= array->capacity) {
array->capacity *= 2;
AnyObject *oldValue = array->value;
memcpy(array->value, oldValue, array->length*sizeof(AnyObject));
free(oldValue);
}
array->length++; //插入指定位置
array->value[index-1] = value;
//将元素后移
for (int i = index; i < array>length; i++) {
array->value[array->length] = array->value[array->length-i];
}
OBJECTRETAIN(value);
return array;
} //获取某个元素
AnyObject getValueIndexAt(Array *array,int index){
assert(index >= 0 && index < array>length);
return array->value[index];
} //销毁
void destroyArray(Array *array){
free(array->value);
free(array);
printf("数组被销毁\n");
}
//打印结果
void printArray(Array *arr){
for (int i = 0; i < arr>length; i++) {
printf("位置:%d,姓名:%s,年龄:%d\n",i, getStringValue(getName((People*)getValueIndexAt(arr, i))),getIntegerValue(getAge((People*)getValueIndexAt(arr, i))));
}
}
  • 接下来就可以来测试数据了.
//  main.m

#import <Foundation>
#import "People.h"
#import "Array.h"
#import "Object.h"
int main(int argc, const char * argv[]) {
@autoreleasepool { Array *arr = newArray(); People *p0 = newPeople(newString("张三"), newInteger(20));
People *p1 = newPeople(newString("李四"), newInteger(16));
People *p2 = newPeople(newString("王五"), newInteger(17));
People *p3 = newPeople(newString("赵二"), newInteger(14));
People *p4 = newPeople(newString("林三"), newInteger(22));
People *p5 = newPeople(newString("小明"), newInteger(18));
People *p6 = newPeople(newString("小红"), newInteger(25));
People *p7 = newPeople(newString("小方"), newInteger(11));
People *p8 = newPeople(newString("小花"), newInteger(19));
People *p9 = newPeople(newString("小兔"), newInteger(22));
People *p10 = newPeople(newString("新人"), newInteger(23)); //增加元素
addElement(arr, (Object *)p0);
addElement(arr, (Object *)p1);
addElement(arr, (Object *)p2);
addElement(arr, (Object *)p3);
addElement(arr, (Object *)p4);
addElement(arr, (Object *)p5);
addElement(arr, (Object *)p6);
addElement(arr, (Object *)p7);
addElement(arr, (Object *)p8);
addElement(arr, (Object *)p9); //释放内存
OBJECTRELEASE((Object*) p0);
OBJECTRELEASE((Object*) p1);
OBJECTRELEASE((Object*) p2);
OBJECTRELEASE((Object*) p3);
OBJECTRELEASE((Object*) p4);
OBJECTRELEASE((Object*) p5);
OBJECTRELEASE((Object*) p6);
OBJECTRELEASE((Object*) p7);
OBJECTRELEASE((Object*) p8);
OBJECTRELEASE((Object*) p9); printf("增加10个元素\n");
printArray(arr); printf("删除第3个元素\n");
//删除第数组中某一个元素
removeIndexAt(arr, 3);
printArray(arr); printf("插入P10成为第4个元素\n");
//插入
insertIndexAt(arr, (Object *)p10, 4);
printArray(arr); OBJECTRELEASE((Object*) p10); printf("查找第5个元素\n");
//index从0开始 查找第5个元素 index=4
printf("位置:%d,姓名:%s,年龄:%d\n",4, getStringValue(getName((People*)getValueIndexAt(arr, 4))),getIntegerValue(getAge((People*)getValueIndexAt(arr, 4)))); //销毁数组
destroyArray(arr); }
return 0;
}
  • 看下结果吧。

C语言基础 - 实现动态数组并增加内存管理

有兴趣的可以研究下哈