Valgrind条件跳转或移动取决于未初始化的值
我有一个从动态分配的字符串中删除多余空格的函数,它工作正常,但我得到了一个关于未初始化变量的valgrind错误,我似乎无法确定它来自哪里。我已经初始化了所有变量,但这并不能解决错误。
下面是我的代码
#include "main.h"
void normalize_wspace2(char *_str);
int main(void)
{
char s[] = " ls -la f1\t folder2 this one\t\t ";
printf("s initial = %s,\n", s);
normalize_wspace2(s);
printf("s normalized = %s,\n", s);
}
void normalize_wspace2(char *_str)
{
size_t i = 0, j = 0;
for (i = 0, j = 0; _str[i] != '\0'; j++, i++)
{
if (_str[i] == ' ' || _str[i] == '\t' || _str[i] == '\v')
{/* if whitespace is matched */
if (i != 0)
{/*only copy a single ' ' to normalized string*/
_str[j] = ' ';
i++;
j++;
}
while (_str[i] == ' ' || _str[i] == '\t' || _str[i] == '\v')
{/* loop through and ignore all other spaces*/
i++;
}
}
_str[j] = _str[i]; /*copy non-whitespace char to normalized string */
}
_str[j] = '\0';
del_twspace(_str);
}
void del_twspace(char *s)
{
size_t i = 0;
int last_char = -1;
if (s == NULL)
{
perror("error: del_twspace passed null\n");
return;
}
while (s[i] != '\0')
{/* find the last char, ignoring any whitespace */
if (s[i] != ' ' && s[i] != '\t' && s[i] != '\n')
last_char = i;
i++;
}
s[last_char + 1] = '\0'; /* set char after last char to null */
}
Valgrind输出
$ valgrind -s --leak-check=full --show-leak-kinds=all --track-origins=yes ./a.out
==8876== Memcheck, a memory error detector
==8876== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==8876== Using Valgrind-3.18.1 and LibVEX; rerun with -h for copyright info
==8876== Command: ./a.out
==8876==
==8876== Conditional jump or move depends on uninitialised value(s)
==8876== at 0x109323: normalize_wspace2 (in /workspaces/103507869/functions/cln/a.out)
==8876== by 0x1091F4: main (in /workspaces/103507869/functions/cln/a.out)
==8876== Uninitialised value was created by a stack allocation
==8876== at 0x109169: main (in /workspaces/103507869/functions/cln/a.out)
==8876==
s initial = ls -la f1 folder2 this one ,
s normalized = ls -la f1 folder2 this one ,
==8876==
==8876== HEAP SUMMARY:
==8876== in use at exit: 0 bytes in 0 blocks
==8876== total heap usage: 1 allocs, 1 frees, 4,096 bytes allocated
==8876==
==8876== All heap blocks were freed -- no leaks are possible
==8876==
==8876== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
==8876==
==8876== 1 errors in context 1 of 1:
==8876== Conditional jump or move depends on uninitialised value(s)
==8876== at 0x109323: normalize_wspace2 (in /workspaces/103507869/functions/cln/a.out)
==8876== by 0x1091F4: main (in /workspaces/103507869/functions/cln/a.out)
==8876== Uninitialised value was created by a stack allocation
==8876== at 0x109169: main (in /workspaces/103507869/functions/cln/a.out)
==8876==
==8876== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
1条答案
按热度按时间ffx8fchx1#
尾随空格出现问题:在这个循环之后
i
将已经是_str
中尾部'\0'
的索引。然后它再次递增for()
,因此下一次检查_str[i] != \0'
已经超出_str
的边界。做解决它你可以只添加
while循环之后,或者将循环体更改为
一个完全不同的解决方案,避免在
for()
循环中写入i
,可能看起来像这样(顺便说一句:我在这里删除了前面的_
,因为这些是重新保存的名称: