C++为void指针分配一个字符串

Question

我有下一个问题。我有这样的功能。

unsigned long FuncTest(void* name) { ... }

当我调用 FuncTest 时，我将制作这种形式

int main()
{

    void* test = NULL;

    cout << "Value of test before to call Function: " << test << endl;

    FuncTest(test);

    cout << "Value of test after to call Function: " << test << endl;
}

我需要 FuncTest 将变量名称的值更改为字符串或字符之类的东西。有可能吗？

我输入了我拥有的代码，但无法正常工作。

void FuncTest(void* name)
{
    char* NewValue = _strdup("Hello!");
    cout << "Value of name in FuncTest before change: " << name << endl;

    name = NewValue;

    cout << "Value of NewValue in FuncTest: " << NewValue << endl;
    cout << "Value of name in FuncTest after change: " << (char*)name << endl;
}

接下来是结果:

Value of test before to call Function: 00000000
Value of name in FuncTest before change: 00000000
Value of NewValue in FuncTest: Hello!
Value of name in FuncTest after change: Hello!
Value of test after to call Function: 00000000

谁能帮帮我谢谢!

Answer 1

您按值将 test 传递给函数，因此您在函数内部对其所做的任何更改都不会反射(reflect)在调用程序中。

您需要通过引用传递它:

void FuncTest(void *&name)