c++ string 中的rfind函数的一点疑问

[爱读庄子的码农]

首先贴一段代码，我用的工具是vs2012，

#include<iostream>
#include<string>
#include<cstring>

using std::cout;
using std::endl;

int main()
{

	std::string str("hello world ABCDEFG hello XYZ");

	std::string::size_type index = str.rfind("hello",0,std::strlen("hello"));

	if(index != std::string::npos)
		for(std::string::size_type i = index ; i < str.size(); ++i)
			cout<<str[i];
	cout<<endl;

	system("pause");
	return 0;
}

vs2012的运行结果如下：


按照我的理解应该是输出 “hello XYZ” 啊，求大神解释解释！谢谢

[fly_dragon_fly]

rfind("hello",0,std::strlen("hello")),你指定了从位置0开始找, 把后面的参数去掉改成rfind("hello")

[pengzhixi]

std::string::size_type index = str.rfind("hello",str.size(),std::strlen("hello"));

[jiqiang01234]

size_type rfind( value_type _Ch, size_type _Off = npos ) const; size_type rfind( const value_type* _Ptr, size_type _Off = npos ) const; size_type rfind( const value_type* _Ptr, size_type _Off, size_type _Count ) const; size_type rfind( const basic_string<CharType, Traits, Allocator>& _Str, size_type _Off = npos ) const; _Ch The character value for which the member function is to search. _Off Index of the position at which the search is to begin. 注意这里，是从源字符串指定的位置开始，反向查找。可不是从字符串尾查找。 _Ptr The C-string for which the member function is to search. _Count The number of characters, counting forward from the first character, in the C-string for which the member function is to search. _Str The string for which the member function is to search.

[苏叔叔]

用这个 std::string::size_type index = str.rfind("hello");