关于valgrind的 “Conditional jump or move depends on uninitialised value(s)”

关于valgrind的 “Conditional jump or move depends on uninitialised value(s)”：

valgrind在报这个错误的时候程序未必有bug，如下例：

 
     
     // 
     test.cpp 
     
 
     #include  
     < 
     iostream 
     > 
     
 
     using 
       
     namespace 
      std;
 
     bool 
      ptr( 
     char 
       
     * 
     testptr)
{
         
     int 
      i 
     = 
     0 
     ;
         
     if 
     (i  
     == 
       
     0 
     ){
                memcpy(testptr, 
     " 
     Hello 
     " 
     , 
     5 
     );
                 
     return 
       
     true 
     ;
        }
         
     return 
       
     false 
     ;
}

 
     int 
      main( 
     int 
      argc,  
     const 
       
     char 
       
     * 
     argv[])
{
         
     char 
       
     * 
     p  
     = 
       
     new 
       
     char 
      [ 
     10 
     ];
         
     if 
     (ptr(p)){
                printf( 
     " 
     %s\n 
     " 
     ,p);
        }

        delete [] p;

         
     return 
       
     0 
     ;
} 
     
   

执行：
g++ test.cpp -Wall
valgrind --tool=memcheck --leak-check=full --show-reachable=yes ./a.out

就会报下面的错：

==8472==
==8472== Conditional jump or move depends on uninitialised value(s)
==8472==    at 0x4906507: strlen (mac_replace_strmem.c:243)
==8472==    by 0x3D26142A0A: vfprintf (in /lib64/tls/libc-2.3.4.so)
==8472==    by 0x3D26148157: printf (in /lib64/tls/libc-2.3.4.so)
==8472==    by 0x4009A6: main (in /home/maoqi/private/cpp/a.out)
Hello
==8472==
==8472== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 5 from 2)
==8472== malloc/free: in use at exit: 0 bytes in 0 blocks.
==8472== malloc/free: 1 allocs, 1 frees, 10 bytes allocated.
==8472== For counts of detected errors, rerun with: -v
==8472== All heap blocks were freed -- no leaks are possible.

因此在遇到这种错误的时候需要仔细分析。