1、测试代码

#include <QCoreApplication>

#pragma pack(push, 1)
typedef struct
{
    int a;
    float b;
    char c;
    int *d;
}testStruct;
#pragma pack(pop)

#include <QByteArray>
#include <QDebug>

int main()
{
    testStruct structA;

    structA.a = 1;
    structA.b = 2;
    structA.c = 'a';
    structA.d = new int[10];

    for (int i = 0; i < 10; ++i) {
        structA.d[i] = i;
    }

    QByteArray arr;

    arr.resize(49);

    memcpy(arr.data(), &structA, 9);

    memcpy(arr.data() + 9, structA.d, 40);
	
	// testStruct *sb = reinterpret_cast<testStruct *>(arr.data());
    testStruct *sb = (testStruct*)arr.data();

    sb->d = reinterpret_cast<int *>(arr.data() + 9);;

    for (int i = 0; i < 10; ++i) {
        qDebug() << sb->d[i];
    }

    return 0;
}

2、输出结果

40642209
0
2
3
4
5
6
7
8
9

3、发现

经过调试指针转换后，发现本来设置的1字节对其变成了4字节对齐
QBytearray的data()指针被转换后会按照4字节自动对齐填充，不知为何会这样
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