Changes between Version 5 and Version 6 of cypress/Programming/CodeDebugging

Timestamp:

08/20/15 21:45:29 (10 years ago)

Author:

fuji

Comment:

—

cypress/Programming/CodeDebugging

@@ -317 +317 @@
 }}}
 
+
+=== Detect Memory Leaks  ===
+
+Example code: (this code has a bug)
+
+{{{#!c++
+#include <iostream>
+#include <cstring>
+
+char * foo() {
+  char *a = new char[200];
+  std::strcpy(a, "hello workshop");
+  return a;
+}
+
+int main() {
+  char * a = foo();
+  char * b = foo();
+  std::cout << "a = " <<  a << std::endl;
+  std::cout << "b = " <<  b << std::endl;
+  return 0;
+}
+}}}
+
+{{{#!bash
+[fuji@cypress1 TestCodes]$ icpc -g mleak.cpp
+[fuji@cypress1 TestCodes]$ valgrind --leak-check=full ./a.out
+==10272== Memcheck, a memory error detector
+==10272== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al.
+==10272== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright info
+==10272== Command: ./a.out
+==10272==
+a = hello workshop
+b = hello workshop
+==10272==
+==10272== HEAP SUMMARY:
+==10272==     in use at exit: 400 bytes in 2 blocks
+==10272==   total heap usage: 2 allocs, 0 frees, 400 bytes allocated
+==10272==
+==10272== 200 bytes in 1 blocks are definitely lost in loss record 1 of 2
+==10272==    at 0x4C28192: operator new[](unsigned long) (vg_replace_malloc.c:363)
+==10272==    by 0x4009D8: foo() (mleak.cpp:5)
+==10272==    by 0x400A0F: main (mleak.cpp:11)
+==10272==
+==10272== 200 bytes in 1 blocks are definitely lost in loss record 2 of 2
+==10272==    at 0x4C28192: operator new[](unsigned long) (vg_replace_malloc.c:363)
+==10272==    by 0x4009D8: foo() (mleak.cpp:5)
+==10272==    by 0x400A20: main (mleak.cpp:12)
+==10272==
+==10272== LEAK SUMMARY:
+==10272==    definitely lost: 400 bytes in 2 blocks
+==10272==    indirectly lost: 0 bytes in 0 blocks
+==10272==      possibly lost: 0 bytes in 0 blocks
+==10272==    still reachable: 0 bytes in 0 blocks
+==10272==         suppressed: 0 bytes in 0 blocks
+==10272==
+==10272== For counts of detected and suppressed errors, rerun with: -v
+==10272== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 6 from 6)
+}}}
+
 == Intel® Inspector XE ==
 Memory and Thread Debugger: