c - 将唯一 char* 添加到链表时出现问题

Question

我正在尝试实现一个数据结构，其中我有一个 char* 值列表和一个数组，该数组存储来自 cmd 行的每个唯一 char* 值的出现次数。这有点乱，但我想我已经弄清楚了，直到我尝试测试它（每个测试不必以不同的方式编译，我只是重命名每次运行以使测试名称不同）。

测试 cmd 输入：

test1 a b c d e f g
test2 a a b b c d d e f f g g
test3 a a a a a a a a a a a
test4 a a a a a a a a a a a b c c
test5 a j i q y z n f o p m a
test6 a a b b c d d e f f g
test7 a j k q e s l i h i a
test8 a j i q y z n f o p m

根据这些输入，每个表格的长度应如下所示：

test1 table->length = 7    <- works
test2 table->length = 7    <- works
test3 table->length = 1    <- works
test4 table->length = 3    <- works
test5 table->length = 11   <- works
test6 table->length = 7    <- no work
test7 table->length = 9    <- no work
test8 table->length = 11   <- no work

基于这些结果，我不相信它的长度argc（因为测试 1、2、3 有效）也不是唯一*chars 的数量（根据测试 2、3、4,5）。运行下面的代码时，它可以工作并且我到达末尾main(...)，或者，根据输入，它会在显示后失败：

...
ptr address: 00DF04F4
ptr value: 00DF0510

测试.c：

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

typedef struct node {
    char *path;
    int index;
    struct node *next;
} node;

typedef struct lookup {
    struct node *head;
    struct node *ptr;
    int length;
    int array[];
} lookup;

void add(lookup *table, char *path);
void search(lookup *table, char *path, int *i);

void add(lookup *table, char *path) {
    int i = 0;
    search(table, path, &i);
    if(table->ptr == NULL) {
        node *new_node = malloc(sizeof(node));
        if (table->head == NULL) {
            table->head = new_node;
            table->head->next = NULL;
            table->head->path = path;
            table->array[0] = 1;
            table->head->index = 0;
            table->length = 1;
        } else {
            new_node->path = path;
            new_node->next = table->head;
            table->head = new_node;
            table->array[i] = 1;
            table->head->index = i;
            table->length += 1;
        }
    } else {
        table->array[table->ptr->index] += 1;
    }
}

void search(lookup *table, char *path, int *i) {
    if(table->head == NULL) {
        table->ptr = NULL;
        return;
    }
    table->ptr = table->head;
    (*i) = 0;
    while(table->ptr != NULL) {
        printf("ptr address: %p\n", &(table->ptr));
        printf("ptr value: %p\n", (table->ptr));
        /* FAILURE POINT */
        printf("%s\n", table->ptr->path);
        printf("comparing ptr string: '%s' with given '%s'\n", table->ptr->path, path);
        if(strcmp(table->ptr->path, path) == 0) {
            printf("found match!\n");
            return;
        }
        table->ptr = table->ptr->next;
        (*i) += 1;
    }
    printf("could not find '%s' in table\n", path);
}

int main(int argc, char **argv) {
    lookup *table = malloc(sizeof(lookup) + argc);
    table->head = NULL;
    int i = 1;
    for(i; i < argc; i++) {
        printf("\n\ntry adding: %s\n", argv[i]);
        add(table, argv[i]);
    }
    printf("\n\n############\nfinished adding\n");
    printf("table length: %d\n", table->length);

    return 0;
}

我知道指针不为空（因为我之前打印了它的地址和值）但我不确定为什么它会在看似正常的输入处停止执行。预期的输出（基于当前代码）应该显示每个char*尝试添加的内容、search(...)搜索表时指针的地址和值、当前*charptr 指向、*char正在比较的两个 s、是否匹配找到，或者如果search(...)找不到*char。

标签： cpointersdata-structures