小编Hig*_*tor的帖子

我有以下结构的3个项目:

App
|  |
  ...
|  |
|  +--lib
|  |    |
|  |    +--...
|  |
|  +--dist
|
Lib
|  |
   ...
|  |
|  +--lib
|  |    |
|  |    +--sublib-1.0.jar
|  |
|  +--dist
|       |
|       +--lib-1.0.jar
|
SubLib
   |
  ... 
   |
   +--dist
        |
        +--sublib-1.0.jar

其中有以下关系:

App <-- Lib <-- SubLib

我使用的Apache常春藤检索都依赖App和Lib.依赖关系描述如下: ivy.xmlof Lib:

<ivy-module version = "2.0">
    <info organisation = "com.test.lib" module = "lib"/>
    <dependencies>
        <dependency org = …

为了理解输入流的工作原理，我设计了以下两个类：

#include <iostream>

class my_streambuf: public std::streambuf
{
private:
  std::streambuf* buffer;

  char ch;

protected:

  virtual std::streambuf::int_type underflow()
  {
    std::streambuf::int_type result = buffer->sbumpc();

    if (result != traits_type::eof())
    {
      ch = traits_type::to_char_type(result);

      setg(&ch, &ch, &ch + 1);
    }

    return result;
  }

public:
  my_streambuf(std::streambuf* buffer) : buffer(buffer) {};

  virtual ~my_streambuf() {};
};

class my_istream: public std::istream
{
public:
  my_istream(std::istream& stream) : std::istream(new my_streambuf(stream.rdbuf())) {};

  virtual ~my_istream()
  {
    delete rdbuf();
  }
};

int main()
{
  char s[32];
  my_istream is(std::cin);

  is >> s;
  std::cout << …

#include <stdio.h>

int main(void)
{
  char s[32];

example_1:
  scanf("%s", s);
  printf("%s\n", s);

example_2:
  scanf("%s", &s[0]);
  printf("%s\n", s);

example_3:
  scanf("%s", &s);
  printf("%s\n", s);
}

1. 为什么#3与其他2的工作方式相同？

2. #3有效吗？为什么？