C++ - 为什么静态字符串在由不同函数引用时会给出稍微不同的地址？

Question

只是试图掌握C++的复杂性,因此正在搞乱字符串和指针.但是,我遇到了一些我不太了解的事情.

首先,我使用相同的功能,据我所知,每次都给它相同的参数.我从主要和另一个函数调用它,并从每个函数获取略有不同的地址.从内存的某些部分读取数据的功能如下.

void printDataFromAddressForLength(char* pointer, long length)
{
    cout << "\n" << endl;

    for (int i=0; i<length; i++)
    {
        cout << "&pointer: " << &pointer + i << "\tData: " << pointer + i << endl;
    }
}

这个函数的目标是在每一行上打印当前地址和值,然后迭代并可以从任何地方做同样的事情 - 非常简单的功能,没有真正的目的.

这是我在main()中的代码

MessageData messageData = returnStruct();
printDataFromAddressForLength(messageData.pChar, messageData.length);

我也从returnStruct()函数调用printDataFromAddressForLength.这段代码如下所示.

// Returns MessageData from function 
MessageData returnStruct()
{
static string staticTestString = "Time and time again";

MessageData metaData;
MessageData* pMetaData = &metaData;

pMetaData->pChar = &staticTestString[0];
pMetaData->length = staticTestString.length();

printDataFromAddressForLength(pMetaData->pChar, pMetaData->length);

return metaData;
}

下面的输出来自于返回struct内部调用的printDataFromAddressForLength()函数.注意:0x0027F*7*

&pointer: 0027F7BC      Data: Time and time again
&pointer: 0027F7C0      Data: ime and time again
&pointer: 0027F7C4      Data: me and time again
&pointer: 0027F7C8      Data: e and time again
&pointer: 0027F7CC      Data:  and time again
&pointer: 0027F7D0      Data: and time again
&pointer: 0027F7D4      Data: nd time again
&pointer: 0027F7D8      Data: d time again
&pointer: 0027F7DC      Data:  time again
&pointer: 0027F7E0      Data: time again
&pointer: 0027F7E4      Data: ime again
&pointer: 0027F7E8      Data: me again
&pointer: 0027F7EC      Data: e again
&pointer: 0027F7F0      Data:  again
&pointer: 0027F7F4      Data: again
&pointer: 0027F7F8      Data: gain
&pointer: 0027F7FC      Data: ain
&pointer: 0027F800      Data: in
&pointer: 0027F804      Data: n

此输出来自main本身调用的printDataFromAddressForLength()函数.注意:0x0027F*8*

&pointer: 0027F8BC      Data: Time and time again
&pointer: 0027F8C0      Data: ime and time again
&pointer: 0027F8C4      Data: me and time again
&pointer: 0027F8C8      Data: e and time again
&pointer: 0027F8CC      Data:  and time again
&pointer: 0027F8D0      Data: and time again
&pointer: 0027F8D4      Data: nd time again
&pointer: 0027F8D8      Data: d time again
&pointer: 0027F8DC      Data:  time again
&pointer: 0027F8E0      Data: time again
&pointer: 0027F8E4      Data: ime again
&pointer: 0027F8E8      Data: me again
&pointer: 0027F8EC      Data: e again
&pointer: 0027F8F0      Data:  again
&pointer: 0027F8F4      Data: again
&pointer: 0027F8F8      Data: gain
&pointer: 0027F8FC      Data: ain
&pointer: 0027F900      Data: in
&pointer: 0027F904      Data: n

据我所知,我首先调用该函数,传入指针和长度.

然后我将包含这两个参数的结构返回到main并使用我期望的相同参数调用相同的函数,长度显然是相同的但是pChar具有奇怪的地址增量.

如有任何见解,将不胜感激!

干杯

Answer 1

您正在打印形式参数'pointer'的地址,而不是字符串的地址.

void printDataFromAddressForLength(char* pointer, long length)
{
    cout << "\n" << endl;

    for (int i=0; i<length; i++)
    {
        cout << "&pointer: " << (void*)(pointer + i) << "\tData: " << pointer + i << endl;
    }
}