我正在从 Zed Shaw 的优秀Learn C the Hard Way中学习C。
我正在使用内核版本 3.9.0-vanillaice amd64(我编译它)和 glibc 2.17(从 Debian 的 repo 安装)运行 Debian Sid。
这是我的代码:
#include <stdio.h>
//This program is purposefully messed up.
int main()
{
int age = 10;
int height;
printf("I am %d years old.\n");
printf("I am %d inches tall.\n", height);
return 0;
}
Valgrind 应该产生这样的东西:
$ valgrind ./ex4
==3082== Memcheck, a memory error detector
==3082== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al.
==3082== Using Valgrind-3.6.0.SVN-Debian and LibVEX; rerun with -h for copyright info
==3082== Command: ./ex4
==3082==
I am -16775432 years old.
==3082== Use of uninitialised value of size 8
==3082== at 0x4E730EB: _itoa_word (_itoa.c:195)
==3082== by 0x4E743D8: vfprintf (vfprintf.c:1613)
==3082== by 0x4E7E6F9: printf (printf.c:35)
==3082== by 0x40052B: main (ex4.c:11)
==3082==
==3082== Conditional jump or move depends on uninitialised value(s)
==3082== at 0x4E730F5: _itoa_word (_itoa.c:195)
==3082== by 0x4E743D8: vfprintf (vfprintf.c:1613)
==3082== by 0x4E7E6F9: printf (printf.c:35)
==3082== by 0x40052B: main (ex4.c:11)
==3082==
==3082== Conditional jump or move depends on uninitialised value(s)
==3082== at 0x4E7633B: vfprintf (vfprintf.c:1613)
==3082== by 0x4E7E6F9: printf (printf.c:35)
==3082== by 0x40052B: main (ex4.c:11)
==3082==
==3082== Conditional jump or move depends on uninitialised value(s)
==3082== at 0x4E744C6: vfprintf (vfprintf.c:1613)
==3082== by 0x4E7E6F9: printf (printf.c:35)
==3082== by 0x40052B: main (ex4.c:11)
==3082==
I am 0 inches tall.
==3082==
==3082== HEAP SUMMARY:
==3082== in use at exit: 0 bytes in 0 blocks
==3082== total heap usage: 0 allocs, 0 frees, 0 bytes allocated
==3082==
==3082== All heap blocks were freed -- no leaks are possible
==3082==
==3082== For counts of detected and suppressed errors, rerun with: -v
==3082== Use --track-origins=yes to see where uninitialised values come from
==3082== ERROR SUMMARY: 4 errors from 4 contexts (suppressed: 4 from 4)
$
我的没有提到错误:
$ valgrind ./ex4
==4098== Memcheck, a memory error detector
==4098== Copyright (C) 2002-2012, and GNU GPL'd, by Julian Seward et al.
==4098== Using Valgrind-3.8.1 and LibVEX; rerun with -h for copyright info
==4098== Command: ./ex4
==4098==
I am -16776056 years old.
I am 0 inches tall.
==4098==
==4098== HEAP SUMMARY:
==4098== in use at exit: 0 bytes in 0 blocks
==4098== total heap usage: 0 allocs, 0 frees, 0 bytes allocated
==4098==
==4098== All heap blocks were freed -- no leaks are possible
==4098==
==4098== For counts of detected and suppressed errors, rerun with: -v
==4098== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 2 from 2)