1. 什么是Prefast

Prefast是一种代码分析工具，它能够帮助你找到编译器不能找到的错误或者缺陷。Prefast首次被微软集成到Visual Studio 2005 Team Suite中去，使用起来非常方便。

2.怎么使用Prefast
在vs2005 Team Suite中，使用Prefast非常简单。修改你的工程属性，设置Enable Code Analysis For C/C++为Yes.



效果:


注意到有可能错误的地方以浅灰色显示在编辑器中了。

3.Prefast能帮你找到哪些错误

1)没有初始化

 // no initial
void  defect1()
{
         int  a;
         int  b;

        b  =  a;
} 

会报: d:\test\testcode\testcode.cpp(18) : warning C6001: Using uninitialized memory 'a': Lines: 15, 16, 18

2)空指针取值

// one path dereference NULL
void  defect4( int  b,  int  c)
{
         int   * p  =  NULL;
         int  a  =   1 ;

         if  (b  ==   1 ) {
                 if  (c  ==   1 ) {
                        p  =   & a;
                }
                 else  {
                                                
                }
        }
         else  {
                 if  (c  ==   1 ) {

                }
                 else  {
                        p  =   & a;
                }
        }

         * p;

         return ;
}  

会报:d:\test\testcode\testcode.cpp(65) : warning C6011: Dereferencing NULL pointer 'p': Lines: 45, 46, 48, 57, 65

3)可能错误的运算符优先级

void  defect5()
{
         int  a  =   1 ;
         int  b  =   1 ;
         int  c  =   1 ;

         if  (a  &  b  ==  c)
                 return ;
} 

会报: d:\test\testcode\testcode.cpp(76) : warning C6281: Incorrect order of operations: relational operators have higher precedence than bitwise operators

4)可能的buffer overrun

void  defect8()
{
         char  buf[ 100 ];
         char  buf2[ 200 ];
         int  i  =   100 ;

        sprintf(buf,  " hello world %d " , i);
        strcpy(buf, buf2);
} 

会报: d:\test\testcode\testcode.cpp(133) : warning C6202: Buffer overrun for 'buf', which is possibly stack allocated, in call to 'strcpy': length '200' exceeds buffer size '100'

5)可能的无穷循环
 

// infinite loop
void  defect14()
{
        signed  char  i;

         for  (i  =   100 ; i  >=   0 ; i ++ ) {
                ; 
        }
} 

会报: d:\test\testcode\testcode.cpp(198) : warning C6292: Ill-defined for-loop: counts up from maximum

6)格式字符串错误

// Format string mismatch
void  defect21()
{
         char  buff[ 5 ];
        sprintf(buff,  " %s %s " ,  " a " );
} 

会报: d:\test\testcode\testcode.cpp(277) : warning C6063: Missing string argument to 'sprintf' that corresponds to conversion specifier '2'

7)安全问题

void  defect27()
{
        CreateProcess(NULL,
                " c:\\program files\\Project.exe arg1 " ,  // correct "\"c:\\program files\\Project.exe\" arg1",
               NULL,
               NULL,
                false ,
                0 ,
               NULL,
               NULL,
               NULL,
               NULL);               
} 

会报: d:\test\testcode\testcode.cpp(327) : warning C6277: NULL application name with an unquoted path in call to 'CreateProcessA': results in a security vulnerability if the path contains spaces

8)=和==误用

void  defect32()
{
         int  a  =   1 ;

         if  (a  =   2 )
                 return ;
} 

会报: d:\test\testcode\testcode.cpp(405) : warning C6282: Incorrect operator: assignment of constant in Boolean context. Consider using '==' instead

9)逻辑运算问题

// always false
void  defect45()
{
         int  x;

         if  ( 0   &&  x ++ ) {
                ;
        }
} 

会报: d:\test\testcode\testcode.cpp(564) : warning C6237: (<zero> && <expression>) is always zero. <expression> is never evaluated and might have side effects

10)其他