如何访问在另一个函数中的一个函数中定义和声明的变量?

2022-01-04 00:00:00 scope c++

谁能告诉我如何访问在另一个函数中的函数中声明和定义的变量.例如

Can anyone tell me how to access variables declared and defined in a function in another function. E.g

void function1()
{
   string abc;
}

void function2()
{
   I want to access abc here.
}

怎么做?我知道使用参数我们可以做到这一点，但还有其他方法吗?

How to do that? I know using parameters we can do that but is there any other way ?

推荐答案

C++的方式是通过引用你的函数来传递abc:

The C++ way is to pass abc by reference to your function:

void function1()
{
    std::string abc;
    function2(abc);
}
void function2(std::string &passed)
{
    passed = "new string";
}

您也可以将字符串作为指针传递并在函数 2 中取消引用它.这更像是 C 风格的做事方式，并不安全(例如，可以传入 NULL 指针，如果没有良好的错误检查，它将导致未定义的行为或崩溃.

You may also pass your string as a pointer and dereference it in function2. This is more the C-style way of doing things and is not as safe (e.g. a NULL pointer could be passed in, and without good error checking it will cause undefined behavior or crashes.

void function1()
{
    std::string abc;
    function2(&abc);
}
void function2(std::string *passed)
{
    *passed = "new string";
}

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