很弱弱的指针问题
这几天刚学到struct和指针，想做一下小练习，但碰到这样的问题弄了半天也没有弄明白这是怎么回事，高手们帮忙解答一下啊，请看======这里

#include<stdio.h>
#include<stdlib.h>
#include<string.h>

struct Dictionary
{
char *word;
int count;
};

int InitStruct(struct Dictionary **dic);
int main()
{
char buffer[20] ={'\0'};
struct Dictionary *dic=NULL;
InitStruct(&dic);
int n = 0;
if(n==0)
{
printf("%s   \r\n",(dic+N)->word);// 这里把0<=N<29都能正常输出 ============= 
}
else
{// 这里连续输出为什么会报错呢？  ==============
printf("%s   \r\n",(dic+9)->word);
printf("%s   \r\n",(dic+15)->word);
printf("%s   \r\n",(dic+15)->word);
printf("%s   \r\n",(dic+15)->word);
printf("%s   \r\n",(dic+15)->word);
}
gets(buffer);
return 0;
}

//初始化struct
int InitStruct(struct Dictionary **dic)
{
struct Dictionary dicTmp[]=
{
{"1",0},
{"2",0},
{"3",0},
{"4",0},
{"5",0},
{"6",0},
{"7",0},
{"8",0},
{"9",0},
{"10",0},
{"11",0},
{"12",0},
{"13",0},
{"14",0},
{"15",0},
{"16",0},
{"17",0},
{"18",0},
{"19",0},
{"20",0},
{"21",0},
{"22",0},
{"23",0},
{"24",0},
{"25",0},
{"26",0},
{"27",0},
{"28",0},
{"29",0},
{"30",0}

};
*dic = dicTmp;
return 0;
}

指针 struct
[解决办法]
先不考虑输出结果的对错，代码里面InitStruct函数的做法本身就是错误的。dicTemp的内存是在栈上分配的，所以InitStruct函数返回之后，这片内存就会被销毁。结果正确只是偶然情况。

正确的做法是，使用malloc来分配内存，或者使用全局变量。
[解决办法]
注意需要分配内存：

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
 
struct Dictionary
{
    char *word;
    int count;
};
 
int InitStruct(struct Dictionary **dic); 
 
int main()
{
    char buffer[20] ={'\0'};
    struct Dictionary *dic=(struct Dictionary *)malloc(sizeof(struct Dictionary) * 60);       
    InitStruct(&dic);
    int n = 2;
    if(n==0)
    {
        printf("%s   \r\n",(dic+n)->word);// 这里把0<=N<29都能正常输出 ============= 
    }
    else
    {// 这里连续输出为什么会报错呢？  ==============
        printf("%s   \r\n",(dic+9)->word);   
        printf("%s   \r\n",(dic+15)->word);
        printf("%s   \r\n",(dic+15)->word);
        printf("%s   \r\n",(dic+15)->word);
        printf("%s   \r\n",(dic+15)->word);
    }   
    gets(buffer);
    return 0;
}
 
//初始化struct
int InitStruct(struct Dictionary **dic)
{
    struct Dictionary dicTmp[]=
    {
        {"1",0},
        {"2",0},
        {"3",0},
        {"4",0},
        {"5",0},
        {"6",0},
        {"7",0},
        {"8",0},
        {"9",0},
        {"10",0},
        {"11",0},
        {"12",0},
        {"13",0},
        {"14",0},
        {"15",0},
        {"16",0},
        {"17",0},
        {"18",0},
        {"19",0},
        {"20",0},
        {"21",0},
        {"22",0}, 
 
        {"23",0},
        {"24",0},
        {"25",0},
        {"26",0},
        {"27",0},
        {"28",0},
        {"29",0},
        {"30",0}
 
    };
    //*dic = dicTmp;
    memcpy(*dic, dicTmp, sizeof(dicTmp));
    return 0;
}

引用:

这几天刚学到struct和指针，想做一下小练习，但碰到这样的问题弄了半天也没有弄明白这是怎么回事，高手们帮忙解答一下啊，请看======这里

#include<stdio.h>
#include<stdlib.h>
#include<string.h>

struct Dictionary
{
char *word;
int count;
};

int InitStruct(struct Dictionary **dic);
int main()
{
char buffer[20] ={'\0'};
struct Dictionary *dic=NULL;
InitStruct(&dic);
int n = 0;
if(n==0)
{
printf("%s   \r\n",(dic+N)->word);// 这里把0<=N<29都能正常输出 ============= 
}
else
{// 这里连续输出为什么会报错呢？  ==============
printf("%s   \r\n",(dic+9)->word);
printf("%s   \r\n",(dic+15)->word);
printf("%s   \r\n",(dic+15)->word);
printf("%s   \r\n",(dic+15)->word);
printf("%s   \r\n",(dic+15)->word);
}
gets(buffer);
return 0;
}

//初始化struct
int InitStruct(struct Dictionary **dic)
{
struct Dictionary dicTmp[]=
{
{"1",0},
{"2",0},
{"3",0},
{"4",0},
{"5",0},
{"6",0},
{"7",0},
{"8",0},
{"9",0},
{"10",0},
{"11",0},
{"12",0},
{"13",0},
{"14",0},
{"15",0},
{"16",0},
{"17",0},
{"18",0},
{"19",0},
{"20",0},
{"21",0},
{"22",0},
{"23",0},
{"24",0},
{"25",0},
{"26",0},
{"27",0},
{"28",0},
{"29",0},
{"30",0}

};
*dic = dicTmp;
return 0;
}

[解决办法]

引用:

Quote: 引用:

先不考虑输出结果的对错，代码里面InitStruct函数的做法本身就是错误的。dicTemp的内存是在栈上分配的，所以InitStruct函数返回之后，这片内存就会被销毁。结果正确只是偶然情况。

正确的做法是，使用malloc来分配内存，或者使用全局变量。

能不能给一个例子啊，这块不是很懂，这样我好理解，我初学者，还有好多东西要学呢，谢了。

//改成这样把，加个关键字 static
 static struct Dictionary dicTmp[]=
    {
        {"1",0},
        {"2",0},
        {"3",0},
        {"4",0},
        {"5",0},
        {"6",0},
        {"7",0},
        {"8",0},
        {"9",0},
        {"10",0},
        {"11",0},
        {"12",0},
        {"13",0},
        {"14",0},
        {"15",0},
        {"16",0},
        {"17",0},
        {"18",0},
        {"19",0},
        {"20",0},
        {"21",0},
        {"22",0},
        {"23",0},
        {"24",0},
        {"25",0},
        {"26",0},
        {"27",0},
        {"28",0},
        {"29",0},
        {"30",0}
 
    };

看看c primer plus 里面的 指针数组这块知识吧！





[解决办法]
dicTemp的内存是在栈上分配的，所以InitStruct函数返回之后，这片内存就会被销毁
[解决办法]
static struct Dictionary dicTmp[]=