如果我在这种情况下使用 malloc 会不会有任何内存泄漏

Question

int num_words = 0;
while ((c = fgetc(in_fp)) != EOF) {
    if (c == 32 || c == 10 || c == 13 || c == 46) {
        //32 is Space, 10 is LF, 13 is CR, 46 is period
        //todo: Add other kinds of punctuation
        num_words = num_words + 1;
    }
}                                   

char** words = (char**) malloc(num_words * sizeof(char*));
if (words == NULL) {
    printf("Memory allocation failed\n");
    return 1; //abort program
}

//Reset the input file pointer to the start of the file
rewind(in_fp);

//Allocate enough space for each word
int word_being_allocated = 0;
int word_size = 0;
int size;
while ((c = fgetc(in_fp)) != EOF) {
    if (c == 32 || c == 10 || c == 13 || c == 46) {
        //32 is Space, 10 is LF, 13 is CR, 46 is period
        size = (word_size + 1) * sizeof(char);
        words[word_being_allocated] = (char*) malloc(size);
        if (words[word_being_allocated] == NULL) {
            printf("Memory allocation failed\n");
            return 1;
        }
        word_being_allocated = word_being_allocated + 1;
        word_size = 0;
        continue;
    }
    word_size = word_size + 1;
}
for (int i = 0; i < num_words; i++) {
    free(words[i]);
}
free(words);

会不会有内存泄漏，因为我用了两次malloc。我的问题是因为我已经为 **words 分配内存，当我写 words[word_being_allocated] = (char*) malloc(size);是不是又分配了。

Answer 1

据我们所见，只要您不丢弃任何malloc()ed 内存，您提供的代码就可以了。所以至少你有机会做到无泄漏。你是否真的是取决于你在处理数据后如何进行。

Answer 2

只要您使用free() 分配的每个内存块malloc()，您都不会发生内存泄漏。

编辑在这段代码中：

while ((c = fgetc(in_fp)) != EOF) {
    if (c == 32 || c == 10 || c == 13 || c == 46) {
        //32 is Space, 10 is LF, 13 is CR, 46 is period
        size = (word_size + 1) * sizeof(char);
        words[word_being_allocated] = (char*) malloc(size);

你似乎没有更新word_being_allocated，所以你可能会覆盖words数组中的same指针槽，在这种情况下会泄漏内存（因为你没有@987654326 @之前分配的指针）。

当您正确更新word_being_allocated 时，请确保不溢出words 指针数组的边界。