为什么这段代码有内存泄漏

Why this code has memory leakage?

本文关键字：内存 泄漏 代码 段代码 为什么      更新时间：2023-10-16

我检查了每一行，但找不到忘记删除的地方。我在这个网站上找到了AllocateDynamicArray和FreeDynamicArray代码，并假设它是正确的。我将尽快提供瓦尔格林德输出。任何帮助将不胜感激。

template <typename T>
T **AllocateDynamicArray(int nRows, int nCols) {
    T **dynamicArray;
    dynamicArray = new T*[nRows];
    for (int i = 0; i < nRows; i++) {
        dynamicArray[i] = new T [nCols];
        for (int j = 0; j < nCols; j++) {
            dynamicArray[i][j] = 0;
        }
    }
    return dynamicArray;
}

template <typename T>
void FreeDynamicArray(T** dArray, int nRows) {
    for (int i = 0; i < nRows; i++) {
        delete[] dArray[i];
    }
    delete[] dArray;
}
int main(int argc, char* argv[]) {
    int numOfComps = 1;
    int** input = AllocateDynamicArray<int>(rowNo, 4);
    while (calculateAvgTime(false) > maxAvgTime) {
        numOfComps++;
    }
    FreeDynamicArray(input, rowNo);
    return EXIT_SUCCESS;
}

double calculateAvgTime(bool print) {
    double waitingTime = 0;
    int* computers = new int[numOfComps];
    for (int i = 0; i < numOfComps; i++) {
        computers[i] = 0;
    }
    int** infoList = AllocateDynamicArray<int>(numOfComps, 2);
    //some code related to computers and infoList
    double waitingTime /= (double) (rowNo);
    FreeDynamicArray(infoList, numOfComps);
    delete[] computers;
    return waitingTime;
}

以下是瓦尔格林德的输出。 

==21109== 
==21109== HEAP SUMMARY:
==21109==     in use at exit: 1,344 bytes in 4 blocks
==21109==   total heap usage: 72 allocs, 68 frees, 11,752 bytes allocated
==21109== 
==21109== 336 bytes in 1 blocks are definitely lost in loss record 1 of 2
==21109==    at 0x4C28D27: operator new[](unsigned long) (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==21109==    by 0x402159: Heap::Heap(int) (in /home/cs/c_turhan/bin/HW3/simulator/simulator)
==21109==    by 0x401977: calculateAvgTime(bool) (in /home/cs/c_turhan/bin/HW3/simulator/simulator)
==21109==    by 0x401792: main (in /home/cs/c_turhan/bin/HW3/simulator/simulator)
==21109== 
==21109== 1,008 bytes in 3 blocks are definitely lost in loss record 2 of 2
==21109==    at 0x4C28D27: operator new[](unsigned long) (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==21109==    by 0x402159: Heap::Heap(int) (in /home/cs/c_turhan/bin/HW3/simulator/simulator)
==21109==    by 0x401977: calculateAvgTime(bool) (in /home/cs/c_turhan/bin/HW3/simulator/simulator)
==21109==    by 0x401724: main (in /home/cs/c_turhan/bin/HW3/simulator/simulator)
==21109== 
==21109== LEAK SUMMARY:
==21109==    definitely lost: 1,344 bytes in 4 blocks
==21109==    indirectly lost: 0 bytes in 0 blocks
==21109==      possibly lost: 0 bytes in 0 blocks
==21109==    still reachable: 0 bytes in 0 blocks
==21109==         suppressed: 0 bytes in 0 blocks
==21109== 
==21109== For counts of detected and suppressed errors, rerun with: -v
==21109== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 6 from 6)

在calculateAvgTime中，你在computers中分配一个数组，但你只释放了一个项目。每当使用new[]时，请使用delete[]。

更好的是，只需使用vector并观察该程序的内存管理问题消失。

我没有看到定义"rowNo"的位置，因此可能存在"FreeDynamicArray（）"未删除所有内存的问题，此外，如果您使用的是VS，请尝试获取视觉泄漏检测器（此处），它将帮助您跟踪泄漏的内存并帮助您查明错误。

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