了解valgrind输出

Question

我是linux新手。我怎样才能解释下面的输出：

valgrind --tool=memcheck --leak-check=yes ./main 

它说一些块丢失。我如何确定内存泄漏。

==2599== HEAP SUMMARY: 
==2599==  in use at exit: 17,327 bytes in 55 blocks 
==2599== total heap usage: 180,597 allocs, 180,542 frees, 15,787,989,675 bytes allocated 
==2599== 
==2599== 9 bytes in 1 blocks are definitely lost in loss record 5 of 19 
==2599== at 0x4025BD3: malloc (vg_replace_malloc.c:236) 
==2599== by 0x41E546F: strdup (strdup.c:43) 
==2599== by 0x804BA2A: Schema::Schema(char*, char*) (Schema.cc:86) 
==2599== by 0x804AD78: CNF::GrowFromParseTree(AndList*, Schema*, Record&) (Comparison.cc:606) 
==2599== by 0x804EE52: main (main.cc:28) 
==2599== 
==2599== 10 bytes in 2 blocks are definitely lost in loss record 6 of 19 
==2599== at 0x4025BD3: malloc (vg_replace_malloc.c:236) 
==2599== by 0x41E546F: strdup (strdup.c:43) 
==2599== by 0x804BB84: Schema::Schema(char*, char*) (Schema.cc:115) 
==2599== by 0x804AD78: CNF::GrowFromParseTree(AndList*, Schema*, Record&) (Comparison.cc:606) 
==2599== by 0x804EE52: main (main.cc:28) 
==2599== 
==2599== 13 bytes in 1 blocks are definitely lost in loss record 9 of 19 
==2599== at 0x4025BD3: malloc (vg_replace_malloc.c:236) 
==2599== by 0x41E546F: strdup (strdup.c:43) 
==2599== by 0x804BA2A: Schema::Schema(char*, char*) (Schema.cc:86) 
==2599== by 0x804EDF4: main (main.cc:23) 
==2599== 
==2599== 13 bytes in 1 blocks are definitely lost in loss record 10 of 19 
==2599== at 0x4025BD3: malloc (vg_replace_malloc.c:236) 
==2599== by 0x41E546F: strdup (strdup.c:43) 
==2599== by 0x804BA2A: Schema::Schema(char*, char*) (Schema.cc:86) 
==2599== by 0x804EEA4: main (main.cc:37) 
==2599== 
==2599== 188 bytes in 16 blocks are definitely lost in loss record 16 of 19 
==2599== at 0x4025BD3: malloc (vg_replace_malloc.c:236) 
==2599== by 0x41E546F: strdup (strdup.c:43) 
==2599== by 0x804BB84: Schema::Schema(char*, char*) (Schema.cc:115) 
==2599== by 0x804EDF4: main (main.cc:23) 
==2599== 
==2599== 188 bytes in 16 blocks are definitely lost in loss record 17 of 19 
==2599== at 0x4025BD3: malloc (vg_replace_malloc.c:236) 
==2599== by 0x41E546F: strdup (strdup.c:43) 
==2599== by 0x804BB84: Schema::Schema(char*, char*) (Schema.cc:115) 
==2599== by 0x804EEA4: main (main.cc:37) 
==2599== 
==2599== LEAK SUMMARY: 
==2599== definitely lost: 421 bytes in 37 blocks 
==2599== indirectly lost: 0 bytes in 0 blocks 
==2599==  possibly lost: 0 bytes in 0 blocks 
==2599== still reachable: 16,906 bytes in 18 blocks 
==2599==   suppressed: 0 bytes in 0 blocks 
==2599== Reachable blocks (those to which a pointer was found) are not shown. 
==2599== To see them, rerun with: --leak-check=full --show-reachable=yes 
==2599== 
==2599== For counts of detected and suppressed errors, rerun with: -v 
==2599== ERROR SUMMARY: 6 errors from 6 contexts (suppressed: 19 from 8) 

Answer 1

输出显示一清二楚的堆栈即泄漏（和丢失，即没有指向这仍然）分配内存，在线条86和Schema.cc（一个strdup呼叫）的115

Answer 2

从OpenGroup的的strdup()描述：

的的strdup（）函数将返回一个指针到一个新的字符串，它是字符串的复制到s1指向的。返回的指针可以传递给free（）。如果无法创建新字符串，则返回空指针。

总之，strdup()正在调用malloc()。你需要free()这个结果字符串，当你完成它。虽然，当你使用C++时，如果可以的话，我会强烈推荐std::string。请记住，如果你真的需要C等价物string.c_str()将得到它。