Valgrind，即使我自由了，块肯定会丢失？

Question

Small Note, Please Ignore the use of malloc instead of new and the use of my own containers instead of vector etc... The point of this code was to practice the basics.

当我运行 Valgrind 我得到：

==24855== HEAP SUMMARY:
==24855==     in use at exit: 0 bytes in 2 blocks
==24855==   total heap usage: 12,999 allocs, 12,997 frees, 675,432 bytes allocated
==24855==
==24855== 0 bytes in 1 blocks are definitely lost in loss record 1 of 2
==24855==    at 0x4C29F73: malloc (vg_replace_malloc.c:309)
==24855==    by 0x4014ED: ImageTagger::GetAllSegmentsByLabel(int, int**, int**, int*) (ImageTagger.cpp:100)
==24855==    by 0x402EB6: GetAllSegmentsByLabel (library2.cpp:59)
==24855==    by 0x403A8B: OnGetAllSegmentssByLabel (main2.cpp:345)
==24855==    by 0x4033A6: parser (main2.cpp:172)
==24855==    by 0x403135: main (main2.cpp:95)
==24855==

但是分配的块在main中被释放了，这是什么问题？这是我的代码的相关部分：

ImageTagger.cpp:

StatusType ImageTagger::GetAllSegmentsByLabel(int label, int **images, int **segments, int *numOfSegments) {
    if (label <= 0 || images == nullptr || segments == nullptr || numOfSegments == nullptr) {
        return INVALID_INPUT;
    }
    *numOfSegments = Match_Num(image_tree->root, label);
    int *imageArr = (int *) malloc(sizeof(int) * (*numOfSegments));
    if (imageArr == nullptr) {
        return ALLOCATION_ERROR;
    }
    int *segArr = (int *) malloc(sizeof(int) * (*numOfSegments));
    if (segArr == nullptr) {
        free(imageArr);
        return ALLOCATION_ERROR;
    }
    int counter = 0;
    InorderTraversal(image_tree->root, imageArr, segArr, &counter, (*numOfSegments), label);
    *images = imageArr;
    *segments = segArr;
    if ((*numOfSegments) == 0) {
        *images = *segments = nullptr;
    }
    return SUCCESS;
}

并且在 main2.cpp 中我有（注意末尾的两条空闲行，那是怎么丢失的？）：

static errorType OnGetAllSegmentssByLabel(void* DS, const char* const command) {
    int courseID, numOfLabels;
    int *images, *segments;
    ValidateRead(sscanf(command, "%d", &courseID), 1, "%s failed.\n", commandStr[GETALLSEGMENTSSBYLABEL_CMD]);
    StatusType res = GetAllSegmentsByLabel(DS, courseID, &images, &segments, &numOfLabels);

    free(images);
    free(segments);

    return error_free;
}

Answer 1

如果 (*numOfSegments) == 0 在 GetAllSegmentsByLabel 中为真会怎样？

在那种情况下，您仍然分配了 2 个 0 字节的块，但它们丢失了，因为您在 if 语句中退出函数之前将两个指针都设置为 nullptr。

必须释放包括 malloc(0) 在内的每个 malloc。

Valgrind，即使我自由了，块肯定会丢失？

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