char 指针的动态数组
我试图定义一个包含指向字符串的字符指针的动态数组。字符串可以是任意长度，所以我使用了 char 指针。我想在每次需要存储更多值时动态调整数组的大小。下面的代码给了我分段错误。我做得好吗？
int main() {
char **input=NULL;
char *buffer;
int i=0;
do {
input = (char **)realloc(input, (i+1) * sizeof(char *));
scanf("%s", &buffer);
strcpy(input[i++],buffer);
} while(strlen(buffer)!=0);
}
I am trying to define a dynamic array containing char pointers that point to strings. The string can be of any length, so i used char pointers. I want to dynamically resize the array each time I need to store more values. The following code gives me segmentation fault. Am I doing it well?
int main() {
char **input=NULL;
char *buffer;
int i=0;
do {
input = (char **)realloc(input, (i+1) * sizeof(char *));
scanf("%s", &buffer);
strcpy(input[i++],buffer);
} while(strlen(buffer)!=0);
}
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问题是您将 buffer 定义为指针，但没有将其指向可以保存扫描字符串的对象，因此 scanf 在未分配的内存中写入，这实际上是坏的。您也没有分配
input[i]，因此strcpy也会失败。您可能想更改为使用strdup代替：另外一些挑剔：扫描字符串时，您不需要字符串缓冲区上的
&，因此重做像这样：并且您不应该强制转换
realloc（或malloc）的结果：The problem is that you define
bufferas a pointer, but you do not point it to something that can hold the scanned string, soscanfwrites out in unallocated memory which is really bad. You also do not allocateinput[i]sostrcpywill also fail. You might want to change that to usestrdupinstead:Another couple of nitpicks: When scanning for a string, you do not need the
&on the string buffer, so redo like this:And you should not cast the result of
realloc(ormalloceither for that matter):除了其他答案中已经列出的问题之外，循环永远不会终止，因为：
在读取至少一个字符（不包括行尾字符）之前不会返回。
In addition to the issues already listed in the other answers the loop will never terminate as:
will not return until it reads at least one character, excluding the end of line character.
您的缓冲区和输入[i]未分配。
Your buffer and your input[i] are not allocated.
您的代码中有多个问题。除非您修复所有这些问题，否则它不会起作用
缓冲区分配内存。 Scanf 会写入稀薄的空气，如果不是下一点可以说是更严重的buffer传递给 scanf，而不是&buffer< /strong>input[i]分配内存。你只是分配输入的内存。There are multiple issues in your code. It won't work until you fix all of them
buffer. Scanf would write into thin air, if it weren't for the next point which is arguably more seriousbufferto scanf, not&bufferinput[i]. You are only allocatingmemory for
input.缓冲区未初始化。此外， &buffer 是一个指向指针的指针，而不是您可能想要的字符数组。
buffer is uninitialized. Besides &buffer is a pointer to a pointer, not to a character array, as you probably intend.