java及C++中传值传递、引用传递和指针方式的理解

public class Test {   
   
  /**   
   * @param args   
   */  
  public static void main(String[] args) {     
    StringBuffer buffer= new StringBuffer("colin");   
    SChange(buffer);   
    System.out.println( buffer);   
  }   
      
  public static void SChange (StringBuffer str) {   
    str= new StringBuffer("huang");   
  }   
   
}

public class Test {   
   
  /**   
   * @param args   
   */  
  public static void main(String[] args) {     
    StringBuffer buffer= new StringBuffer("colin");   
    SChange(buffer);   
    System.out.println( buffer);   
  }   
      
  public static void SChange (StringBuffer str) {   
    //str= new StringBuffer("huang");       str.append(" huang");   
  }   
   
}

#include <stdio.h> 
#include <iostream> 
#include <typeinfo> 
void ByValue(int a) 
{ 
  a = a + 1; 
} 
 void ByRef(int& a) 
{ 
  a = a + 1; 
} 
 void ByPointer(int* a) 
{ 
  *a = *a + 1; 
} 
 int main(int argv, char** args) 
{ 
  int v = 1; 
  ByValue(v); 
  ByRef(v); 
 
  // Pass by Reference   ByPointer(&v); 
 
  // Pass by Value   int* vp = &v; 
  ByPointer(vp); 
   
  std::cout << v << std::endl; // std::cout << typeid(vp).name() << std::endl;  
// std::cout << typeid(&vp).name() << std::endl;    std::cout << "end" << std::endl; 
}