Octopress 的第一篇文章，簡單介紹 Valgrind - 檢查程式記憶體的小工具

前陣子我對 project 進行 Debug 其中有一些 runtime error, 包含 memory leak

我使用 Valgrind 來檢查 Memory Leak

小範例，由 Valgrind 找出 test.cpp 第8行的 Bug ( Invalid read )

{% codeblock lang:cpp %} #include #include using namespace std ;

int main() { vector array(1024); cout << array[1024] << endl ; return 0; } {% endcodeblock %}

$g++ -g test.cpp $valgrind ./a.out

輸出訊息 {% codeblock %} ==9247== Memcheck, a memory error detector ==9247== Copyright © 2002-2011, and GNU GPL’d, by Julian Seward et al. ==9247== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright info ==9247== Command: ./a.out ==9247== ==9247== Invalid read of size 8 ==9247== at 0x80487C4: main (test.cpp:8) ==9247== Address 0x4336028 is 0 bytes after a block of size 8,192 alloc’d ==9247== at 0x402B9B4: operator new(unsigned int) (in /usr/lib/valgrind/vgpreload_memcheck-x86-linux.so) ==9247== by 0x8048BD1: __gnu_cxx::new_allocator::allocate(unsigned int, void const*) (new_allocator.h:92) ==9247== by 0x8048B1D: std::_Vector_base >::_M_allocate(unsigned int) (in /home/stanleyhsiao/a.out) ==9247== by 0x80489BC: std::_Vector_base >::_Vector_base(unsigned int, std::allocator const&) (stl_vector.h:123) ==9247== by 0x80488D1: std::vector >::vector(unsigned int, double const&, std::allocator const&) (stl_vector.h:265) ==9247== by 0x80487A3: main (test.cpp:7) ==9247== 0 ==9247== ==9247== HEAP SUMMARY: ==9247== in use at exit: 0 bytes in 0 blocks ==9247== total heap usage: 1 allocs, 1 frees, 8,192 bytes allocated ==9247== ==9247== All heap blocks were freed – no leaks are possible ==9247== ==9247== For counts of detected and suppressed errors, rerun with: -v ==9247== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0) {% endcodeblock %}