嵌入式学习第十五天

本文主要是介绍嵌入式学习第十五天，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

1.内存管理:
1.malloc
void *malloc(size_t size);
功能:
申请堆区空间
参数:
size:申请堆区空间的大小
返回值:
返回获得的空间的首地址
失败返回NULL

2.free
void free(void *ptr);
功能:
释放堆区空间

注意:
1.free只能释放堆区空间
2.一个空间只能被free一次,多次free程序会崩溃
3.malloc需要和free搭配使用,如果只有malloc没有free会内存泄露

练习:要求申请堆区空间,将"hello world"存放到堆区空间,完成打印

2.内存溢出:
内存溢出也称为内存越界

3.内存泄露:
程序中malloc的空间没有被释放

4.内存碎片:
由于频繁申请和释放,导致连续的空间分散成一些小的碎片空间,当malloc超过碎片空间时,则无法获得该空间（空间不连续）,将这样的空间称为内存碎片

==================================================================================================================================================
链表:

1 #include <stdio.h>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              2 #include <string.h>3 #include <stdlib.h>4 5 typedef int DataType;6 7 typedef struct node 8 {9     DataType Data;10     struct node *pNext;11 }LinkNode;12 13 LinkNode *CreateLinkList(void)14 {15     LinkNode *pTmpNode = NULL;16 17     pTmpNode = malloc(sizeof(LinkNode));18     if (NULL == pTmpNode)19     {20         return NULL;21     }22 23     pTmpNode->pNext = NULL;24     25     return pTmpNode;26 }27 28 int InsertHeadLinkList(LinkNode *pHead, DataType TmpData)29 {30     LinkNode *pTmpNode = NULL;31 32     pTmpNode = malloc(sizeof(LinkNode));33     if (NULL == pTmpNode)34     {35         return -1;36     }37 38     pTmpNode->Data = TmpData;39     pTmpNode->pNext = pHead->pNext;40     pHead->pNext = pTmpNode;41 42     return 0;43 }44 45 int ShowLinkList(LinkNode *pHead)46 {47     LinkNode *pTmpNode = NULL;48 49     pTmpNode = pHead->pNext;50     while (pTmpNode != NULL)51     {52         printf("%d ", pTmpNode->Data);53         pTmpNode = pTmpNode->pNext;54     }55     printf("\n");56 57     return 0;58 }59 60 int ReplaceLinkList(LinkNode *pHead, DataType OldData, DataType NewData)61 {62     LinkNode *pTmpNode = NULL;63 64     pTmpNode = pHead->pNext;65     while (pTmpNode != NULL)66     {67         if (pTmpNode->Data == OldData)68         {69             pTmpNode->Data = NewData;70         }71         pTmpNode = pTmpNode->pNext;72     }73 74     return 0;75 }76 77 int DeleteLinkList(LinkNode *pHead, DataType TmpData)78 {79     LinkNode *pPreNode = NULL;80     LinkNode *pTmpNode = NULL;81 82     pTmpNode = pHead->pNext;83     pPreNode = pHead;84     85     while (pTmpNode != NULL)86     {87         if (pTmpNode->Data == TmpData)88         {89             pPreNode->pNext = pTmpNode->pNext;90             free(pTmpNode);91             pTmpNode = pPreNode->pNext;92         }93         else 94         {95             pTmpNode = pTmpNode->pNext;96             pPreNode = pPreNode->pNext;97         }98     }99 
100     return 0;
101 }
102 
103 int DestroyLinkList(LinkNode **ppHead)
104 {
105     LinkNode *pTmpNode = NULL;
106     LinkNode *pFreeNode = NULL;
107 
108     pTmpNode = pFreeNode = *ppHead;
109     while (pTmpNode != NULL)
110     {
111         pTmpNode = pTmpNode->pNext;
112         free(pFreeNode);
113         pFreeNode = pTmpNode;
114     }
115     *ppHead = NULL;
116 
117     return 0;
118 }
119 
120 int InsertTailLinkList(LinkNode *pHead, DataType TmpData)
121 {
122     LinkNode *pTmpNode = NULL;
123     LinkNode *pTailNode = NULL;
124 
125     pTailNode = pHead;
126     pTmpNode = malloc(sizeof(LinkNode));
127     if (pTmpNode == NULL)
128     {
129         return -1;
130     }
131     while (pTailNode->pNext != NULL)
132     {
133         pTailNode = pTailNode->pNext;
134     }
135 
136     pTmpNode->Data = TmpData;
137     pTmpNode->pNext = NULL;
138     pTailNode->pNext = pTmpNode;
139 
140     return 0;
141 }
142 int main(void)
143 {
144     LinkNode *linklist = NULL;
145 
146     linklist = CreateLinkList();
147     InsertHeadLinkList(linklist, 1);
148     InsertHeadLinkList(linklist, 2);
149     InsertHeadLinkList(linklist, 3);
150     InsertHeadLinkList(linklist, 4);
151     InsertHeadLinkList(linklist, 5);
152     ShowLinkList(linklist);
153     ReplaceLinkList(linklist, 5, 50);
154     ReplaceLinkList(linklist, 1, 10);
155     ShowLinkList(linklist);
156     DeleteLinkList(linklist, 50);
157     DeleteLinkList(linklist, 10);
158     ShowLinkList(linklist);
159     InsertTailLinkList(linklist,30);
160     ShowLinkList(linklist);
161 
162     return 0;
163 }

作业:
1.封装函数在链表中实现尾插法
int InsertTailLinkList(LinkNode *pHead, DataType TmpData);

2.从终端接收一个字符串,将字符串倒置后输出
"how are you"

"you are how"

  1 #include <stdio.h>                                                                                                                                                                                                                                                                                            2 #include <string.h>3 4 int Inversion(char *phead,char *ptail)5 {6     char tmp = 0;7 8 9     while (phead < ptail)10     {11         tmp = *phead;12         *phead = *ptail;13         *ptail = tmp;14         phead++;15         ptail--;16     }17 18     return 0;19 }20 21 int main(void)22 {23     char str[32] = {0};24     char *head = NULL;25     char *tail = NULL;26     char *p = NULL;27     char *q = NULL;28     int i = 0;29 30     gets(str);31 32     head = str;33     tail = str + strlen(str) - 1;34 35     Inversion(head,tail);36 37     p = &str[0];38 39     while (str[i] != '\0')40     {41         if (str[i] == ' ')42         {43             Inversion(p,&str[i-1]);44             p = &str[i+1];45         }46         i++;47 48     }49 50     Inversion(p,&str[i-1]);51 52     printf("str = %s\n",str);53 54     return 0;55 }