Program received signal SIGSEGV, Segmentation fault.段错误调试

一、可能的原因                                                                                                    

1、指针未初始化

[easie@localhost zxxtest]$ g++ -o bugging -g bugging.cc                                    #编译程序得到可执行文件，这里一定要添加-g才能调试[easie@localhost zxxtest]$ ./bugging                                                       #运行可执行文件please input a string:zxxSegmentation fault (core dumped)                                                           #段错误          [easie@localhost zxxtest]$ gdb bugging                                                     #用GDB调试GNU gdb (GDB) Fedora (7.4.50.20120120-54.fc17)Copyright (C) 2012 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 "i686-redhat-linux-gnu".For bug reporting instructions, please see:<http://www.gnu.org/software/gdb/bugs/>...Reading symbols from /home/easie/test/Aqua-Sim-1.0/zxxtest/bugging...done.(gdb) l                                                                                     #源程序，错误应该是gets函数接收字符串之前string未被初始化                                                                                            #可用buff为string初始化，为了避免安全性隐患，使用scanf接收1#include "cstdlib"                                                                   2#include "cstdio"3static char buff[256];4static char *string;5int main()6{7  for(int i=0;i<256;i++){buff[i]=0;}8//string=buff;9  printf("please input a string:");10  gets(string);(gdb) r                                                                         #运行程序Starting program: /home/easie/test/Aqua-Sim-1.0/zxxtest/bugging please input a string:zxxProgram received signal SIGSEGV, Segmentation fault. #段错误_IO_gets (buf=0x0) at iogets.c:5555 buf[0] = (char) ch;(gdb) where                                                                      #where非常好用，直接找到了出错的地方在第10行#0 _IO_gets (buf=0x0) at iogets.c:55#1 0x0804851c in main () at bugging.cc:10(gdb)list                                                      #可能是指针未初始化，我每次run之后再list就不是原来的源程序了，我还没找到原因50 /* This is very tricky since a file descriptor may be in the51 non-blocking mode. The error flag doesn't mean much in this52 case. We return an error only when there is a new error. */53 int old_error = _IO_stdin->_IO_file_flags & _IO_ERR_SEEN;54 _IO_stdin->_IO_file_flags &= ~_IO_ERR_SEEN;55 buf[0] = (char) ch;56 count = INTUSE(_IO_getline) (_IO_stdin, buf + 1, INT_MAX, '\n', 0) + 1;57 if (_IO_stdin->_IO_file_flags & _IO_ERR_SEEN)58 {59 retval = NULL;(gdb) list 72 This file is part of the GNU C Library.34 The GNU C Library is free software; you can redistribute it and/or5 modify it under the terms of the GNU Lesser General Public6 License as published by the Free Software Foundation; either7 version 2.1 of the License, or (at your option) any later version.89 The GNU C Library is distributed in the hope that it will be useful,10 but WITHOUT ANY WARRANTY; without even the implied warranty of11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU(gdb) main 7 signal Undefined maintenance command: "7 signal". Try "help maintenance".(gdb) man 7 signalUndefined command: "man". Try "help".(gdb) man 7 signal|grep SEGVUndefined command: "man". Try "help".(gdb) QA debugging session is active.Inferior 1 [process 17662] will be killed.Quit anyway? (y or n) Y[easie@localhost zxxtest]$ man 7 signal|grep SEGV          #通过man 7 signal查看SIGSEGV的信息 signals, such as SIGSEGV and SIGFPE, generated as a consequence of exe‐ SIGSEGV 11 Core Invalid memory reference

所以，定义了指针后记得初始化，在使用的时候记得判断是否为NULL。

修改后的程序如下：

1#include "cstdlib"                                                                   2#include "cstdio"3static char buff[256];4static char *string;5int main()6{7  for(int i=0;i<256;i++){buff[i]=0;}8 string=buff;  //初始化string9  printf("please input a string:");10 // gets(string);11     scanf("%[^\n]",string);//获取屏幕输入的字符串

2、在使用数组的时候是否被初始化，数组下标是否越界，数组元素是否存在等
例如：

#include <stdio.h>intmain(){char test[1];printf(”%c”, test[1000000000]);return 0;}

3、在变量处理的时候变量的格式控制是否合理等
例如：

#include <stdio.h>intmain(){int b = 10;printf(”%s/n”, b);return 0;}

比如，试图把char型或者是int的按照%s输出或存放起来，类似的，还有诸如：sprintf等的格式控制问题

#include <stdio.h>#include <string.h>char c=’c';int i=10;char buf[100];printf(”%s”, c); //试图把char型按照字符串格式输出printf(”%s”, i); //试图把int型按照字符串输出memset(buf, 0, 100);sprintf(buf, “%s”, c); //试图把char型按照字符串格式转换memset(buf, 0, 100);sprintf(buf, “%s”, i); //试图把int型按照字符串转换

二、调试方法
用GDB调试，参考第一条即可，运用r，where，list等命令

参考文章：http://blog.csdn.net/love_gaohz/article/details/6597857