valgrind使用入门

　　valgrind：a suite of tools for debugging and profiling programs

　　1）简介：Valgrind用于调试、分析Linux的可执行文件。

　　2）安装：

yum install valgrind.x86_64 # yum search valgrind

　　3）常用选项：--tool=<toolname>：运行Valgrind的工具。默认是memcheck，其他可用值有cachegrind、callgrind等。

　　4）示例：

int main()
{
    int *p1 = new int;

    int *p2 = NULL;
    cout << *p2 << endl;

    return 0;
}

　　编译（加-g选项）得到a.out，再执行valgrind ./a.out，以下是其输出：

==16564== Memcheck, a memory error detector # 默认使用memcheck工具
... ...
==16564== Invalid read of size 4 # 在test.cpp第9行出现非法内存访问（且size为4）
==16564==    at 0x4008B2: main (test.cpp:9)
==16564==  Address 0x0 is not stack'd, malloc'd or (recently) free'd
... ...
==16564== Process terminating with default action of signal 11 (SIGSEGV)
==16564==  Access not within mapped region at address 0x0
==16564==    at 0x4008B2: main (test.cpp:9)
... ...
==16564== HEAP SUMMARY:
==16564==     in use at exit: 4 bytes in 1 blocks # 内存泄漏情况
==16564==   total heap usage: 1 allocs, 0 frees, 4 bytes allocated
==16564== 
==16564== LEAK SUMMARY:
==16564==    definitely lost: 0 bytes in 0 blocks
==16564==    indirectly lost: 0 bytes in 0 blocks
==16564==      possibly lost: 0 bytes in 0 blocks
==16564==    still reachable: 4 bytes in 1 blocks
==16564==         suppressed: 0 bytes in 0 blocks
... ...
Segmentation fault

不断学习中。。。