Calloc导致分段错误
Calloc导致分段错误
提问于 2011-07-23 11:19:11
下面是我的代码：
#include <stdio.h>
#include <stdlib.h>
int main(){
int n=10;
char *s= calloc(2,sizeof(char));
sprintf(s,"%d",n);
printf(s);
return 0;
}其目的是将2位数加到a (char *)。当我运行代码时，我得到了分段错误。valgrind的输出是-
==18540== Command: ./test
==18540==
==18540== Conditional jump or move depends on uninitialised value(s)
==18540== at 0x366C06F397: _IO_str_init_static_internal (in /lib64/libc-2.5.so)
==18540== by 0x366C063C8A: vsprintf (in /lib64/libc-2.5.so)
==18540== by 0x366C04D677: sprintf (in /lib64/libc-2.5.so)
==18540== by 0x4004FC: main (test.c:8)
==18540==
==18540== Conditional jump or move depends on uninitialised value(s)
==18540== at 0x366C06E37B: _IO_default_xsputn (in /lib64/libc-2.5.so)
==18540== by 0x366C043D38: vfprintf (in /lib64/libc-2.5.so)
==18540== by 0x366C063C98: vsprintf (in /lib64/libc-2.5.so)
==18540== by 0x366C04D677: sprintf (in /lib64/libc-2.5.so)
==18540== by 0x4004FC: main (test.c:8)
==18540==
==18540== Conditional jump or move depends on uninitialised value(s)
==18540== at 0x366C06F20A: _IO_str_overflow (in /lib64/libc-2.5.so)
==18540== by 0x366C06E3E3: _IO_default_xsputn (in /lib64/libc-2.5.so)
==18540== by 0x366C043D38: vfprintf (in /lib64/libc-2.5.so)
==18540== by 0x366C063C98: vsprintf (in /lib64/libc-2.5.so)
==18540== by 0x366C04D677: sprintf (in /lib64/libc-2.5.so)
==18540== by 0x4004FC: main (test.c:8)
==18540==
==18540== Use of uninitialised value of size 8
==18540== at 0x366C06F241: _IO_str_overflow (in /lib64/libc-2.5.so)
==18540== by 0x366C06E3E3: _IO_default_xsputn (in /lib64/libc-2.5.so)
==18540== by 0x366C043D38: vfprintf (in /lib64/libc-2.5.so)
==18540== by 0x366C063C98: vsprintf (in /lib64/libc-2.5.so)
==18540== by 0x366C04D677: sprintf (in /lib64/libc-2.5.so)
==18540== by 0x4004FC: main (test.c:8)
==18540==
==18540== Invalid write of size 1
==18540== at 0x366C06F241: _IO_str_overflow (in /lib64/libc-2.5.so)
==18540== by 0x366C06E3E3: _IO_default_xsputn (in /lib64/libc-2.5.so)
==18540== by 0x366C043D38: vfprintf (in /lib64/libc-2.5.so)
==18540== by 0x366C063C98: vsprintf (in /lib64/libc-2.5.so)
==18540== by 0x366C04D677: sprintf (in /lib64/libc-2.5.so)
==18540== by 0x4004FC: main (test.c:8)
==18540== Address 0x0 is not stack'd, malloc'd or (recently) free'd
==18540== 回答 4
Stack Overflow用户
回答已采纳
发布于 2011-07-23 11:21:46
您只需为2个字符分配空间，然后将字符串'10\0‘放入字符串’10\0‘，这需要另一个字符来保存null/0终止字符。因此，您需要分配3个字符才能使此特定示例正常工作。
请阅读C Strings以了解完整的详细信息。
Stack Overflow用户
发布于 2011-07-23 11:22:26
您分配了2个字节，但字符串大小为3：
'1'，'0'，'\0‘(null终止符)在这种情况下结果是未定义的，因为您损坏了堆
另外，当你分配内存时，不要忘记在最后调用free。
Stack Overflow用户
发布于 2011-07-23 11:23:18
您需要为空终止字符串的空字符分配空间。总共有3个字符。
另外，printf(s);应该是：printf("%s", s);
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/6798018
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