[英]Split an array of strings based on character
I have an array of strings similar to this: 我有一个类似于这样的字符串数组:
char* arrStrings[] = {"a", "be", "|", "cgg", "dss", "|", "mmd", "ddd", "\0"}
1) I would like to be able to be able to split this into a set of arrays, based on where the '|' 1)我希望能够根据'|'的位置将其拆分为一组数组 character is. 字符是。
So, after splitting, I would have this: 因此,分割后,我将得到:
a1 = {"a", "be", "\0"}
a2 = {"cgg", "dss", "\0"}
a3 = {"mmd", "ddd", "\0"}
2) After that, I need to create a linked list that has all 3 arrays, like this: 2)之后,我需要创建一个包含所有3个数组的链表,如下所示:
list = {pointer to a1, pointer to a2, pointer to a3}
I'm very confused about it, since there are multiple levels of pointers involved. 我对此非常困惑,因为其中涉及多个级别的指针。 How can I accomplish this? 我该怎么做?
If you can use NULL
as delimiter in the list, you don't need to duplicate the strings, just use an array of pointers to string. 如果可以在列表中使用NULL
作为分隔符,则无需复制字符串,只需使用指向字符串的指针数组即可。
*arrStrings[] = {"a", "be", "|", "cgg", "dss", "|", "mmd", "ddd", ""};
is transformed into 变成
*arr [] = {"a", "be", NULL, "cgg", "dss", NULL, "mmd", "ddd", NULL};
Once you have filled the array you can use an array of pointers to pointer to string to create the list: 填充数组后,可以使用一个指向字符串的指针的数组来创建列表:
*arr [] = {"a", "be", NULL, "cgg", "dss", NULL, "mmd", "ddd", NULL};
**ptr [] = { ^ ^ ^ };
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main(void)
{
/* The array */
char *arrStrings[] = {"a", "be", "|", "cgg", "dss", "|", "mmd", "ddd", ""};
/* Elements of the array */
size_t sz = sizeof(arrStrings) / sizeof(arrStrings[0]);
/* Loop */
size_t i, n = 0;
/* Create an array (VLA) of n pointers */
char *arr[sz];
/* Count the number of delimiters and fill array */
for (i = 0; i < sz; i++) {
/* If we found a delimiter assign NULL */
if (strcmp(arrStrings[i], "|") == 0) {
arr[i] = NULL;
n++;
} else
/* If we found an empty string assign NULL */
if (arrStrings[i][0] == '\0') {
arr[i] = NULL;
} else {
arr[i] = arrStrings[i];
}
}
/* Create an array (VLA) of n delimiters pointers to pointer */
char **ptr[n + 1];
ptr[0] = &arr[0];
for (i = n = 0; i < sz - 1; i++) {
/* For each NULL string push address of array + 1 into ptr */
if (arr[i] == NULL) {
ptr[++n] = &arr[i + 1];
}
}
/* For each pointer to pointer loop and print until NULL */
char **str;
for (i = 0; i <= n; i++) {
str = ptr[i];
printf("%zu)\n", i);
while (*str != NULL) {
printf("\t%s\n", *str);
str++;
}
}
return 0;
}
Output: 输出:
0)
a
be
1)
cgg
dss
2)
mmd
ddd
The first thing you have to know is that an array of strings is a pointer to a fixed number of further pointers to characters 您必须知道的第一件事是,字符串数组是指向固定数量的其他字符指针的指针
arrString --> |_|_|_| ... |_|
| | | |
V V V V
a b | \0
e
therefore you cannot simply update the "|" 因此,您不能简单地更新“ |” element with "\\0" and manage the string as it would be the "strtok" function for example. 元素带有“ \\ 0”并管理字符串,因为它例如是“ strtok”函数。 Rather, you have to allocate three new "char**" array to maintain the three "char*" sequences, and use them to create the list as you prefer. 相反,您必须分配三个新的“ char **”数组来维护三个“ char *”序列,并根据需要使用它们来创建列表。
In case you want to avoid the allocation of new memory space, then you have to implement customized facilities, in order to parse the "char**" array according to its formatting. 如果要避免分配新的内存空间,则必须实现自定义功能,以便根据其格式解析“ char **”数组。 In this way you can really have three pointers to three different positions in "arrString", which define the first sub-string that belongs to the interested array. 这样,您实际上可以拥有三个指向“ arrString”中三个不同位置的指针,这些指针定义了属于感兴趣数组的第一个子字符串。 The final element "|" 最后一个元素“ |” or "\\0" will indicate no further elements belong to it. 或“ \\ 0”表示没有其他元素属于它。 However, as I already said, this requires you implement ad-hoc functions, which avoid to alter the array. 但是,正如我已经说过的那样,这需要您实现即席功能,避免更改数组。
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