C strcpy_s - 缓冲区太小 && 0 错误

Question

我在这条线上有缓冲问题 strcpy_s(*(pWords + word_count), word_length, pWord); 我正在尝试从 argv[1] 中读取一个文件并打印出该文件中的每个单词及其出现，但我不知道出了什么问题..?!?

int main(int argc, char* argv[])
{
    char *delimiters = argv[2];                     // Prose delimiters
    char buf[BUF_LEN];                                       // Buffer for a line of keyboard input
    size_t str_size = INIT_STR_EXT;                          // Current memory to store prose
    char*  filePath = argv[1];
    FILE *fP ;
    char* pStr = malloc(str_size);                           // Pointer to prose to be tokenized
    *pStr = '[=11=]';                                            // Set 1st character to null
    fopen_s(&fP, filePath, "r");
    fread(buf, BUF_LEN, 10, fP);





    size_t maxWords = 10;                                     // Current maximum word count
    int word_count = 0;                                       // Current word count
    size_t word_length = 0;                                   // Current word length
    char** pWords = calloc(maxWords, sizeof(char*));          // Stores pointers to the words
    int* pnWord = calloc(maxWords, sizeof(int));              // Stores count for each word

    size_t str_len = strnlen_s(buf, BUF_LEN);                // Length used by strtok_s()
    char* ptr = NULL;                                          // Pointer used by strtok_s()
    char* pWord = strtok_s(buf, delimiters, &ptr);  // Find 1st word

    if (!pWord)
    {
        printf("No words found. Ending program.\n");
        return 1;
    }

    bool new_word = true;                                     // False for an existing word
    while (pWord)
    {
        // Check for existing word
        for (int i = 0; i < word_count; ++i)
        if (strcmp(*(pWords + i), pWord) == 0)
        {
            ++*(pnWord + i);
            new_word = false;
            break;
        }

        if (new_word)                                            // Not NULL if new word
        {
            //Check for sufficient memory
            if (word_count == maxWords)
            { // Get more space for pointers to words
                maxWords += WORDS_INCR;
                pWords = realloc(pWords, maxWords*sizeof(char*));

                // Get more space for word counts
                pnWord = realloc(pnWord, maxWords*sizeof(int));
            }

            // Found a new word so get memory for it and copy it there
            word_length = ptr - pWord;      // Length of new word
            *(pWords + word_count) = malloc(word_length);         
            strcpy_s(*(pWords + word_count), word_length, pWord); // Copy to array
            *(pnWord + word_count++) = 1;                         // Increment word count
        }
        else
            new_word = true;                                      // Reset new word flag

        pWord = strtok_s(NULL, delimiters, &ptr);      // Find subsequent word
    }

Answer 1

strcpy_s 在字符串末尾添加一个空字节。你需要 malloc(word_length+1).

Answer 2

在我看来，您好像忘记为 0 字符获取一个额外的字节。尽管如此：您可以使用 SEEK_END 和偏移量 0 来使用 fseek 获取文件大小，而不是为您的文件分配固定的缓冲区大小，以分配那么多内存+1字节

Answer 3

这条线有两个问题：

fread(buf, BUF_LEN, 10, fP);

首先，当您读取 10 个元素时，缓冲区太小了 10 倍。

其次，它读取文件的距离不会超过 BUF_LEN（之前是 *10）。

此外，代码不处理 newline 个字符，因为我无法在 argv[2] 定界符规范中传递它，即使 " \n".

建议你把fread()换成fgets()的循环，重新定义分隔符这个词

#define BUF_LEN 1000                        // plenty of room
...
char buf[BUF_LEN+1];                        // allow for 0 terminator
char delimiters[] = " \n\t";                // predefined
...
//size_t str_len = strnlen_s(buf, BUF_LEN); // unnecessary
while (fgets(buf, BUF_LEN, fP) != NULL) {   // new outer loop
    char* ptr = NULL;                       // carry on as you were
    ...
}

接下来按照其他人的评论，增加字符串space分配

*(pWords + word_count) = malloc(word_length+1);

此外，虽然您使用了"safe"字符串函数，但您没有检查argc或fopen_s()、fread()、malloc()、calloc()、realloc()，也没有关闭文件或释放内存。

C strcpy_s - 缓冲区太小 && 0 错误

C strcpy_s - Buffer is too small && 0 error

c

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