如何使用 GDB 查詢 C 和 C++ 中的分段錯誤?
分段錯誤是執行時錯誤之一,該錯誤是由記憶體訪問違例引起的,例如訪問無效的陣列索引、指向某些限制性地址等。在本文中,我們將看到如何使用 GDB 工具檢測此類錯誤。
讓我們看看程式碼和定位錯誤的相應步驟。
示例
#include <stdio.h> main() { int* ptr = NULL; *ptr = 1; //trying to access unknown memory location printf("%p\n", ptr); }
使用“gcc –g program_name.c”編譯程式碼,並使用“./a.out”執行。
輸出
soumyadeep@soumyadeep-VirtualBox:~/Cpp_progs$ ./a.out Segmentation fault (core dumped)
發生分段錯誤。
編寫“gdb ./a.out core”
soumyadeep@soumyadeep-VirtualBox:~/Cpp_progs$ gdb ./a.out core GNU gdb (Ubuntu 8.1-0ubuntu3) 8.1.0.20180409-git Copyright (C) 2018 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html> This is free software: you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law. Type "show copying" and "show warranty" for details. This GDB was configured as "x86_64-linux-gnu". Type "show configuration" for configuration details. For bug reporting instructions, please see: <http://www.gnu.org/software/gdb/bugs/>. Find the GDB manual and other documentation resources online at: <http://www.gnu.org/software/gdb/documentation/>. For help, type "help". Type "apropos word" to search for commands related to "word"... Reading symbols from ./a.out...done. /home/soumyadeep/Cpp_progs/core: No such file or directory. (gdb)
鍵入“r”,然後按回車鍵。
Starting program: /home/soumyadeep/Cpp_progs/a.out Program received signal SIGSEGV, Segmentation fault. 0x000055555555465e in main () at 1230.find_seg_error.c:5 5 *ptr = 1; //trying to access unknown memory location (gdb)
因此,我們已成功獲取錯誤,現在退出 GDB
(gdb) quit A debugging session is active. Inferior 1 [process 2794] will be killed. Quit anyway? (y or n) y
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