我想遍历一个字符串 vector 并按空格拆分每个字符串。但它抛出一个错误， 我使用 print 来查找错误:
for(int client_i=0; client_i<l.size();client_i++){
...
}
错误不会发生在client_i=0，因为它可以打印所有成功消息一次，但我确定 vector 大小是2，所以它应该打印所有成功消息两次。
======= Backtrace: =========
/lib64/libc.so.6(+0x81609)[0x7f05ad207609]
/lib64/libstdc++.so.6(_ZNSsD1Ev+0x43)[0x7f05adb28b63]
./assignment1[0x404d8a]
./assignment1[0x4044ba]
./assignment1[0x403d17]
./assignment1[0x403477]
./assignment1[0x402e46]
./assignment1[0x40645c]
./assignment1[0x406017]
./assignment1[0x4065ee]
/lib64/libc.so.6(__libc_start_main+0xf5)[0x7f05ad1a8495]
./assignment1[0x401e79]
======= Memory map: ========
00400000-00409000 r-xp 00000000 00:2a 49026461 /home/csdue/yichenwa/cse489589_assignment1/yichenwa/assignment1
00609000-0060a000 rw-p 00009000 00:2a 49026461 /home/csdue/yichenwa/cse489589_assignment1/yichenwa/assignment1
00c43000-00c64000 rw-p 00000000 00:00 0 [heap]
7f05a8000000-7f05a8021000 rw-p 00000000 00:00 0
7f05a8021000-7f05ac000000 ---p 00000000 00:00 0
7f05acb53000-7f05acb69000 r-xp 00000000 08:08 1835074 /usr/lib64/libresolv-2.17.so
7f05acb69000-7f05acd68000 ---p 00016000 08:08 1835074 /usr/lib64/libresolv-2.17.so
7f05acd68000-7f05acd69000 r--p 00015000 08:08 1835074 /usr/lib64/libresolv-2.17.so
7f05acd69000-7f05acd6a000 rw-p 00016000 08:08 1835074 /usr/lib64/libresolv-2.17.so
7f05acd6a000-7f05acd6c000 rw-p 00000000 00:00 0
7f05acd6c000-7f05acd71000 r-xp 00000000 08:08 1835062 /usr/lib64/libnss_dns-2.17.so
7f05acd71000-7f05acf71000 ---p 00005000 08:08 1835062 /usr/lib64/libnss_dns-2.17.so
7f05acf71000-7f05acf72000 r--p 00005000 08:08 1835062 /usr/lib64/libnss_dns-2.17.so
7f05acf72000-7f05acf73000 rw-p 00006000 08:08 1835062 /usr/lib64/libnss_dns-2.17.so
7f05acf73000-7f05acf7f000 r-xp 00000000 08:08 1835064 /usr/lib64/libnss_files-2.17.so
7f05acf7f000-7f05ad17e000 ---p 0000c000 08:08 1835064 /usr/lib64/libnss_files-2.17.so
7f05ad17e000-7f05ad17f000 r--p 0000b000 08:08 1835064 /usr/lib64/libnss_files-2.17.so
7f05ad17f000-7f05ad180000 rw-p 0000c000 08:08 1835064 /usr/lib64/libnss_files-2.17.so
7f05ad180000-7f05ad186000 rw-p 00000000 00:00 0
7f05ad186000-7f05ad348000 r-xp 00000000 08:08 1835046 /usr/lib64/libc-2.17.so
7f05ad348000-7f05ad548000 ---p 001c2000 08:08 1835046 /usr/lib64/libc-2.17.so
7f05ad548000-7f05ad54c000 r--p 001c2000 08:08 1835046 /usr/lib64/libc-2.17.so
7f05ad54c000-7f05ad54e000 rw-p 001c6000 08:08 1835046 /usr/lib64/libc-2.17.so
7f05ad54e000-7f05ad553000 rw-p 00000000 00:00 0
7f05ad553000-7f05ad568000 r-xp 00000000 08:08 1850415 /usr/lib64/libgcc_s-4.8.5-20150702.so.1
7f05ad568000-7f05ad767000 ---p 00015000 08:08 1850415 /usr/lib64/libgcc_s-4.8.5-20150702.so.1
7f05ad767000-7f05ad768000 r--p 00014000 08:08 1850415 /usr/lib64/libgcc_s-4.8.5-20150702.so.1
7f05ad768000-7f05ad769000 rw-p 00015000 08:08 1850415 /usr/lib64/libgcc_s-4.8.5-20150702.so.1
7f05ad769000-7f05ad86a000 r-xp 00000000 08:08 1835054 /usr/lib64/libm-2.17.so
7f05ad86a000-7f05ada69000 ---p 00101000 08:08 1835054 /usr/lib64/libm-2.17.so
7f05ada69000-7f05ada6a000 r--p 00100000 08:08 1835054 /usr/lib64/libm-2.17.so
7f05ada6a000-7f05ada6b000 rw-p 00101000 08:08 1835054 /usr/lib64/libm-2.17.so
7f05ada6b000-7f05adb54000 r-xp 00000000 08:08 1835336 /usr/lib64/libstdc++.so.6.0.19
7f05adb54000-7f05add53000 ---p 000e9000 08:08 1835336 /usr/lib64/libstdc++.so.6.0.19
7f05add53000-7f05add5b000 r--p 000e8000 08:08 1835336 /usr/lib64/libstdc++.so.6.0.19
7f05add5b000-7f05add5d000 rw-p 000f0000 08:08 1835336 /usr/lib64/libstdc++.so.6.0.19
7f05add5d000-7f05add72000 rw-p 00000000 00:00 0
7f05add72000-7f05add94000 r-xp 00000000 08:08 1850417 /usr/lib64/ld-2.17.so
7f05adf8a000-7f05adf93000 rw-p 00000000 00:00 0
7f05adf93000-7f05adf94000 r--p 00021000 08:08 1850417 /usr/lib64/ld-2.17.so
7f05adf94000-7f05adf95000 rw-p 00022000 08:08 1850417 /usr/lib64/ld-2.17.so
7f05adf95000-7f05adf96000 rw-p 00000000 00:00 0
7ffe298ca000-7ffe298eb000 rw-p 00000000 00:00 0 [stack]
7ffe29937000-7ffe29939000 r-xp 00000000 00:00 0 [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]
Abort
我运行 valgrind --leak-check=yes 来检查..这是结果: 很难理解:(
valgrind --leak-check=yes ./assignment1 c 3434
==15589== Memcheck, a memory error detector
==15589== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==15589== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==15589== Command: ./assignment1 c 3434
==15589==
==15589== Conditional jump or move depends on uninitialised value(s)
==15589== at 0x4019BD3: index (in /usr/lib64/ld-2.17.so)
==15589== by 0x4007510: expand_dynamic_string_token (in /usr/lib64/ld-2.17.so)
==15589== by 0x400799C: fillin_rpath (in /usr/lib64/ld-2.17.so)
==15589== by 0x40082D8: _dl_init_paths (in /usr/lib64/ld-2.17.so)
==15589== by 0x4003466: dl_main (in /usr/lib64/ld-2.17.so)
==15589== by 0x4017F2D: _dl_sysdep_start (in /usr/lib64/ld-2.17.so)
==15589== by 0x4001BB0: _dl_start (in /usr/lib64/ld-2.17.so)
==15589== by 0x4001127: ??? (in /usr/lib64/ld-2.17.so)
==15589== by 0x2: ???
==15589== by 0xFFF000442: ???
==15589== by 0xFFF000450: ???
==15589== by 0xFFF000452: ???
==15589==
==15589== Conditional jump or move depends on uninitialised value(s)
==15589== at 0x4019BE2: index (in /usr/lib64/ld-2.17.so)
==15589== by 0x4007510: expand_dynamic_string_token (in /usr/lib64/ld-2.17.so)
==15589== by 0x400799C: fillin_rpath (in /usr/lib64/ld-2.17.so)
==15589== by 0x40082D8: _dl_init_paths (in /usr/lib64/ld-2.17.so)
==15589== by 0x4003466: dl_main (in /usr/lib64/ld-2.17.so)
==15589== by 0x4017F2D: _dl_sysdep_start (in /usr/lib64/ld-2.17.so)
==15589== by 0x4001BB0: _dl_start (in /usr/lib64/ld-2.17.so)
==15589== by 0x4001127: ??? (in /usr/lib64/ld-2.17.so)
==15589== by 0x2: ???
==15589== by 0xFFF000442: ???
==15589== by 0xFFF000450: ???
==15589== by 0xFFF000452: ???
==15589==
==15589== Conditional jump or move depends on uninitialised value(s)
==15589== at 0x4019BF1: index (in /usr/lib64/ld-2.17.so)
==15589== by 0x4007510: expand_dynamic_string_token (in /usr/lib64/ld-2.17.so)
==15589== by 0x400799C: fillin_rpath (in /usr/lib64/ld-2.17.so)
==15589== by 0x40082D8: _dl_init_paths (in /usr/lib64/ld-2.17.so)
==15589== by 0x4003466: dl_main (in /usr/lib64/ld-2.17.so)
==15589== by 0x4017F2D: _dl_sysdep_start (in /usr/lib64/ld-2.17.so)
==15589== by 0x4001BB0: _dl_start (in /usr/lib64/ld-2.17.so)
==15589== by 0x4001127: ??? (in /usr/lib64/ld-2.17.so)
==15589== by 0x2: ???
==15589== by 0xFFF000442: ???
==15589== by 0xFFF000450: ???
==15589== by 0xFFF000452: ???
==15589==
==15589== Conditional jump or move depends on uninitialised value(s)
==15589== at 0x4019B90: index (in /usr/lib64/ld-2.17.so)
==15589== by 0x4007510: expand_dynamic_string_token (in /usr/lib64/ld-2.17.so)
==15589== by 0x40084DC: _dl_map_object (in /usr/lib64/ld-2.17.so)
==15589== by 0x400130D: map_doit (in /usr/lib64/ld-2.17.so)
==15589== by 0x400F703: _dl_catch_error (in /usr/lib64/ld-2.17.so)
==15589== by 0x4001DE9: handle_ld_preload (in /usr/lib64/ld-2.17.so)
==15589== by 0x40042A1: dl_main (in /usr/lib64/ld-2.17.so)
==15589== by 0x4017F2D: _dl_sysdep_start (in /usr/lib64/ld-2.17.so)
==15589== by 0x4001BB0: _dl_start (in /usr/lib64/ld-2.17.so)
==15589== by 0x4001127: ??? (in /usr/lib64/ld-2.17.so)
==15589== by 0x2: ???
==15589== by 0xFFF000442: ???
==15589==
==15589== Conditional jump or move depends on uninitialised value(s)
==15589== at 0x4019B9F: index (in /usr/lib64/ld-2.17.so)
==15589== by 0x4007510: expand_dynamic_string_token (in /usr/lib64/ld-2.17.so)
==15589== by 0x40084DC: _dl_map_object (in /usr/lib64/ld-2.17.so)
==15589== by 0x400130D: map_doit (in /usr/lib64/ld-2.17.so)
==15589== by 0x400F703: _dl_catch_error (in /usr/lib64/ld-2.17.so)
==15589== by 0x4001DE9: handle_ld_preload (in /usr/lib64/ld-2.17.so)
==15589== by 0x40042A1: dl_main (in /usr/lib64/ld-2.17.so)
==15589== by 0x4017F2D: _dl_sysdep_start (in /usr/lib64/ld-2.17.so)
==15589== by 0x4001BB0: _dl_start (in /usr/lib64/ld-2.17.so)
==15589== by 0x4001127: ??? (in /usr/lib64/ld-2.17.so)
==15589== by 0x2: ???
==15589== by 0xFFF000442: ???
==15589==
==15589== Conditional jump or move depends on uninitialised value(s)
==15589== at 0x4019BAE: index (in /usr/lib64/ld-2.17.so)
==15589== by 0x4007510: expand_dynamic_string_token (in /usr/lib64/ld-2.17.so)
==15589== by 0x40084DC: _dl_map_object (in /usr/lib64/ld-2.17.so)
==15589== by 0x400130D: map_doit (in /usr/lib64/ld-2.17.so)
==15589== by 0x400F703: _dl_catch_error (in /usr/lib64/ld-2.17.so)
==15589== by 0x4001DE9: handle_ld_preload (in /usr/lib64/ld-2.17.so)
==15589== by 0x40042A1: dl_main (in /usr/lib64/ld-2.17.so)
==15589== by 0x4017F2D: _dl_sysdep_start (in /usr/lib64/ld-2.17.so)
==15589== by 0x4001BB0: _dl_start (in /usr/lib64/ld-2.17.so)
==15589== by 0x4001127: ??? (in /usr/lib64/ld-2.17.so)
==15589== by 0x2: ???
==15589== by 0xFFF000442: ???
==15589==
==15589== Use of uninitialised value of size 8
==15589== at 0x4C2BA1C: strcpy (vg_replace_strmem.c:506)
==15589== by 0x40628D: hostname_Client() (client.cpp:221)
==15589== by 0x4057E2: setup_Client(int) (client.cpp:55)
==15589== by 0x4065F5: main (yichenwa_assignment1.cpp:77)
==15589==
==15589== Conditional jump or move depends on uninitialised value(s)
==15589== at 0x4C2BA47: is_overlap (vg_replace_strmem.c:128)
==15589== by 0x4C2BA47: strcpy (vg_replace_strmem.c:506)
==15589== by 0x40628D: hostname_Client() (client.cpp:221)
==15589== by 0x4057E2: setup_Client(int) (client.cpp:55)
==15589== by 0x4065F5: main (yichenwa_assignment1.cpp:77)
==15589==
==15589== Conditional jump or move depends on uninitialised value(s)
==15589== at 0x4C2BA53: is_overlap (vg_replace_strmem.c:137)
==15589== by 0x4C2BA53: strcpy (vg_replace_strmem.c:506)
==15589== by 0x40628D: hostname_Client() (client.cpp:221)
==15589== by 0x4057E2: setup_Client(int) (client.cpp:55)
==15589== by 0x4065F5: main (yichenwa_assignment1.cpp:77)
==15589==
==15589== Conditional jump or move depends on uninitialised value(s)
==15589== at 0x4C2BAB8: is_overlap (vg_replace_strmem.c:140)
==15589== by 0x4C2BAB8: strcpy (vg_replace_strmem.c:506)
==15589== by 0x40628D: hostname_Client() (client.cpp:221)
==15589== by 0x4057E2: setup_Client(int) (client.cpp:55)
==15589== by 0x4065F5: main (yichenwa_assignment1.cpp:77)
==15589==
==15589== Conditional jump or move depends on uninitialised value(s)
==15589== at 0x4C2BA62: strcpy (vg_replace_strmem.c:506)
==15589== by 0x40628D: hostname_Client() (client.cpp:221)
==15589== by 0x4057E2: setup_Client(int) (client.cpp:55)
==15589== by 0x4065F5: main (yichenwa_assignment1.cpp:77)
==15589==
我的 hostname_Client() 代码是:
char* hostname_Client(){
...
char *hostname;
strcpy(hostname,hostbuffer);
...
}
最佳答案
char* hostname_Client(){
char hostbuffer[1024]={0};
gethostname(hostbuffer,sizeof(hostbuffer));
char *hostname;
strcpy(hostname,hostbuffer);
return hostname;
}
你永远不会初始化hostname，所以它有一些随机值并且不指向任何东西。然后将它的随机值传递给 strcpy 并告诉它将字符串复制到某个随机位置。
由于您使用的是 C++，您可能希望考虑使用 std::string 而不是 char *，因为它会为您完成大部分内存管理工作。
关于C++:free():下一个大小无效(快速)，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/58187538/