釋放calloc造成分段錯誤

這裏是我的代碼：釋放calloc造成分段錯誤

#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; 
}

目的是assing 2位數的（字符*）。當我運行代碼時，我得到了段錯誤。 Outout從Valgrind的是 -

==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==

來源

2011-07-23 user837208

你只是2個字符分配空間，然後把字符串'10 \ 0' ，這需要另一個字符持有空/ 0終止符。所以你需要爲這個特定的例子分配3個字符來工作。

詳細閱讀C Strings。

來源

2011-07-23 03:21:46

您分配2個字節，但字符串的大小爲3：

「1」，「0」，「\ 0」（零終止子），因爲你破壞堆

結果在這種情況下，未定義

此外，當您分配內存時，不要忘記在最後自由呼叫。

來源

2011-07-23 03:22:26 MByD

另一種解決方案（僅針對這種情況）是'sprintf（s，「％X」，n）;'; -P – MByD

您需要爲空終止字符串的空字符分配空間。總共3個字符。

另外printf(s);應該是：printf("%s", s);

來源

2011-07-23 03:23:18 Paulpro

對於這個特定的代碼串「10」需要3個字節，這是 '1'， '0'，和 '\ 0'。所以你需要分配3個字節的內存。

來源

2011-07-23 03:41:31 phoxis

釋放calloc造成分段錯誤

回答

相關問題