为什么Centos中的gcc给出了此c程序的不同结果

Question

我在计算机上使用Codeblock，并且还使用dev ++对其进行了检查，当我将test.txt作为输入文件和stop.txt给出时，它们都给出相同的正确结果。https://pastebin.com/Z8CPnJNd（test.txt）和https://pastebin.com/qhLU9QV3（stop.txt）

但是，当我在gcc中使用CentOs OS时，它不会从结构列表中删除停用词。例如，必须删除字符串of。

我运行终端，使用命令gcc main.c -o main -std=c99，然后使用./main

我不知道是否有任何const引起了问题，但我已经检查过了。

这是应该执行的部分

typedef struct _word {
    char *s;                /* the word */
    int count;              /* number of times word occurs */
    int *line_numbers;      // Array of line numbers
    int num_line_numbers;   // Size of the array of line numbers
    char *fileno;
} word;

// Creating a struct to hold the data. I find it's easier
typedef struct {
    word *words;      // The array of word structs
    int num_words;    // The size of the array
} word_list;

char *strlower(char *s) {
    for (size_t i = 0; s[i]; i++) {
        s[i] = (char)tolower((unsigned char)s[i]);
    }
    return s;
}
    int remove_word(word_list *words, const char *word_to_delete) {
        int found = 0;
        for (int i = 0; i < words->num_words; i++) {
            if (!strcmp(words->words[i].s, word_to_delete)) {
                // Calc number of words after found word
                int number_of_words_to_right = words->num_words - i - 1;
                // Free mem
                free(words->words[i].s);
                free(words->words[i].line_numbers);
                free(words->words[i].fileno);

                if (--words->num_words == 0) {
                    free(words->words);
                    words->words = NULL;
                } else {
                    // Copy remaining words if any
                    memcpy(&words->words[i], &words->words[i + 1],
                           sizeof(word) * number_of_words_to_right);
                    // Resize the array (technically not required)
                    word *tmp = realloc(words->words, sizeof(word) * words->num_words);
                    if (tmp != NULL)
                        words->words = tmp;
                }
                found++;
                i--; // restart from the same index in the loop
            }
        }
        return found;
    }

main:

int main() {
    int option = 1;
    word_list *words = calloc(sizeof(word_list), 1);
    if (words == NULL) {
        fprintf(stderr, "cannot allocate memory\n");
        return 1;
    }
    read_file(words, "test.txt");


    if (option != 0) {
        char s[1000];
        FILE *file = fopen("stop.txt", "r"); /* should check the result */
        if (file == NULL) {
            fprintf(stderr, "cannot open %s\n", "stop.txt");
        } else {
            while (fgets(s, sizeof(s), file)) {
                char *word = strtok(s, " \n");
                while (word != NULL) {
                    remove_word(words, strlower(word));
                    word = strtok(NULL, " \n");
                }
            }
            fclose(file);
        }
    }
    printlist(words);

    for (int i = 0; i < words->num_words; i++) {
        free(words->words[i].s);
        free(words->words[i].line_numbers);
        free(words->words[i].fileno);
    }
    free(words->words);
    free(words);
    return 0;
}


Code:
https://pastebin.com/aWWHyeyi

Answer 1

It's UB to use memcpy() with overlapping objects。请改用memcpy()。

memmove()