我有一个这样声明的方法:
/*!
\brief Removes the leading and trailing white space from a string.
\param s The string to remove the white space from.
\param white_chars Characters to be considered as whitespace.
*/
std::string Trim(const std::string &s, const std::string &white_chars = " \t\n\r");
该方法的定义是无趣的,但无论如何是这样的:
std::string Trim(const std::string &s, const std::string &white_chars)
{
size_t startidx = s.find_first_not_of(white_chars);
if (startidx == std::string::npos) return "";
size_t endidx = s.find_last_not_of(white_chars);
return s.substr(startidx, endidx - startidx + 1);
}
现在在这种方法的大多数用法中,我只提供第一个参数。Valgrind 给了我以下警告
==3338== 68 bytes in 2 blocks are possibly lost in loss record 4,639 of 7,212
==3338== at 0x4C2B1C7: operator new(unsigned long) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3338== by 0x728CA88: std::string::_Rep::_S_create(unsigned long, unsigned long, std::allocator<char> const&) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.16)
==3338== by 0x728E2B4: char* std::string::_S_construct<char*>(char*, char*, std::allocator<char> const&, std::forward_iterator_tag) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.16)
==3338== by 0x728E414: std::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(std::string const&, unsigned long, unsigned long) (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.16)
==3338== by 0x728E441: std::string::substr(unsigned long, unsigned long) const (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.16)
==3338== by 0x6965F0A: str::Trim(std::string const&, std::string const&) (appbase.cpp:90)
==3338== by 0x5F481D7: netopt::Element::set_ID(std::string const&) (netopt_elem.cpp:85)
注意“块可能丢失”?我已经看到 Valgrind 告诉我“块肯定丢失了”的内存泄漏,但这是一个不太确定的消息。
所以问题就变成了,我是否通过将默认值分配给 a 导致内存泄漏std::string &
?如果是这样,我做错了什么?