用valgrind定位内存泄漏

ubuntu@VM-0-15-ubuntu:~$ man valgrindVALGRIND(1) Release 3.11.0 VALGRIND(1)
NAME valgrind - a suite of tools for debugging and profiling programs
SYNOPSIS valgrind [valgrind-options] [your-program] [your-program-options]
DESCRIPTION Valgrind is a flexible program for debugging and profiling Linux executables. It consists of a core, which provides a synthetic CPU in software, and a series of debugging and profiling tools. The architecture is modular, so that new tools can be created easily and without disturbing the existing structure.
 Some of the options described below work with all Valgrind tools, and some only work with a few or one. The section MEMCHECK OPTIONS and those below it describe tool-specific options.
 This manual page covers only basic usage and options. For more comprehensive information, please see the HTML documentation on your system: $INSTALL/share/doc/valgrind/html/index.html, or online: http://www.valgrind.org/docs/manual/index.html.
TOOL SELECTION OPTIONS The single most important option.
 --tool=<toolname> [default: memcheck] Run the Valgrind tool called toolname, e.g. memcheck, cachegrind, callgrind, helgrind, drd, massif, lackey, none, exp-sgcheck, exp-bbv, exp-dhat, etc.

#include <stdio.h>#include <stdlib.h>char* getMemory(){ char *p = (char *)malloc(30);  return p;} int main(){ char *p = getMemory(); p = NULL;  return 0;}

ubuntu@VM-0-15-ubuntu:~$ g++ -g test.cppubuntu@VM-0-15-ubuntu:~$ubuntu@VM-0-15-ubuntu:~$ubuntu@VM-0-15-ubuntu:~$ valgrind --tool=memcheck --leak-check=yes --show-reachable=yes ./a.out==31560== Memcheck, a memory error detector==31560== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.==31560== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info==31560== Command: ./a.out==31560== ==31560== ==31560== HEAP SUMMARY:==31560== in use at exit: 30 bytes in 1 blocks==31560== total heap usage: 1 allocs, 0 frees, 30 bytes allocated==31560== ==31560== 30 bytes in 1 blocks are definitely lost in loss record 1 of 1==31560== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)==31560== by 0x400537: getMemory() (test.cpp:5)==31560== by 0x40054E: main (test.cpp:11)==31560== ==31560== LEAK SUMMARY:==31560== definitely lost: 30 bytes in 1 blocks==31560== indirectly lost: 0 bytes in 0 blocks==31560== possibly lost: 0 bytes in 0 blocks==31560== still reachable: 0 bytes in 0 blocks==31560== suppressed: 0 bytes in 0 blocks==31560== ==31560== For counts of detected and suppressed errors, rerun with: -v==31560== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)

#include <stdio.h>#include <stdlib.h>char* getMemory(){ char *p = (char *)malloc(30);  return p;} int main(){ char *p = getMemory(); if(p != NULL) { free(p); p = NULL; }  return 0;}

ubuntu@VM-0-15-ubuntu:~$ g++ -g test.cppubuntu@VM-0-15-ubuntu:~$ubuntu@VM-0-15-ubuntu:~$ubuntu@VM-0-15-ubuntu:~$ valgrind --tool=memcheck --leak-check=yes --show-reachable=yes ./a.out==2839== Memcheck, a memory error detector==2839== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.==2839== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info==2839== Command: ./a.out==2839== ==2839== ==2839== HEAP SUMMARY:==2839== in use at exit: 0 bytes in 0 blocks==2839== total heap usage: 1 allocs, 1 frees, 30 bytes allocated==2839== ==2839== All heap blocks were freed -- no leaks are possible==2839== ==2839== For counts of detected and suppressed errors, rerun with: -v==2839== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)ubuntu@VM-0-15-ubuntu:~$