c语言段错误及调试总结.docVIP

标准C语言段错误总结 C语言 2009-02-17 11:49:51 阅读21 评论0 ??字号：大中小?订阅 A segmentation fault (often shortened to segfault) is a particular error condition that can occur during the operation of computer software. In short, a segmentation fault occurs when a program attempts to access a memory location that it is not allowed to access, or attempts to access a memory location in a way that is not allowed (e.g., attempts to write to a read-only location, or to overwrite part of the operating system). Systems based on processors like the Motorola 68000 tend to refer to these events as Address or Bus errors.Segmentation is one approach to memory management and protection in the operating system. It has been superseded by paging for most purposes, but much of the terminology of segmentation is still used, segmentation fault being an example. Some operating systems still have segmentation at some logical level although paging is used as the main memory management policy.On Unix-like operating systems, a process that accesses invalid memory receives the SIGSEGV signal. On Microsoft Windows, a process that accesses invalid memory receives the STATUS_ACCESS_VIOLATION exception. 另外，这里有个基本上对照的中文解释，来自/html_sql/3/132559.htm 所谓的段错误就是指访问的内存超出了系统所给这个程序的内存空间，通常这个值是由gdtr来保存的，他是一个48位的寄存器，其中的32位是保存由它指向的gdt表，后13位保存相应于gdt的下标，最后3位包括了程序是否在内存中以及程序的在cpu中的运行级别,指向的gdt是由以64位为一个单位的表，在这张表中就保存着程序运行的代码段以及数据段的起始地址以及与此相应的段限和页面交换还有程序运行级别还有内存粒度等等的信息。一旦一个程序发生了越界访问，cpu就会产生相应的异常保护，于是segmentation fault就出现了 通过上面的解释，段错误应该就是访问了不可访问的内存，这个内存区要么是不存在的，要么是受到系统保护的。2。为什么段错误这么麻烦？中国linux论坛有一篇精华帖子《Segment fault 之永远的痛》(/forum/gshowflat.php?Cat=Board=programNumber=193239page=2view=collapsedsb=5o=allfpart=1vc=1)在主题帖子里头，作者这么写道： 写程序好多年了，Segment fault 是许多C程序员头疼的提示。指针是好东西，但是随着指针的使用却诞生了这个同样威力巨大的恶魔。Segment fault 之所以能够流行于世，是与Glibc库中基本所有的函数都默认型参指针为非空有着密切关系的。不知道什么时候才可以有能够处理NULL的glibc库诞生啊！不得已，我现在为好多的函数做了衣服，避免glibc的函数被NULL给感染，导致我的Mem访问错误，而我还不知道NULL这个病毒已经在侵蚀我的身体了。Segment fault 永远的痛 ??? 后面有好多网友都跟帖了，讨论了Segmentation faults为什