C ++：为什么解引用这个向量迭代器segfault？ [英] C++: Why does dereferencing this vector iterator segfault?

问题描述

void insert_string( std::vector<std::string> & strings, const std::string &s )
{

    std::vector<std::string>::iterator it=lower_bound(strings.begin(),strings.end(),s);
    if(strings.size()>0) std::cout<<*it<<" is found\n"; // ****
    strings.insert(it,s);
}

尝试使用此功能时，第二个插入将输出[firststring] is found，然后segfault。如果我注释掉if / cout行，我可以反复调用，没有segfaults发生。

When attempting to use this function, the first insertion goes fine. The second insertion will output "[firststring] is found" and then segfault. If I comment out the if/cout line, I can repeatedly call and no segfaults occur.

我也尝试过像 std :: string tmp = * it; ，然后segfault那条线。虽然打印不是一个巨大的交易，我真正想做的是检查在lower_bound找到的位置的字符串是否与尝试插入的字符串相同（即 if（ * it == s），这是像上面两个例子的segfaulting）。

I've also tried doing something like std::string tmp=*it; which will then segfault on that line. While printing is not a huge deal, what I'm really trying to do is check if the string at the position found by lower_bound is the same as the string that is trying to be inserted (i.e., if(*it==s), which is segfaulting just like the above two examples).

我在这里缺少什么？

谢谢！

推荐答案

检查 it == strings.end（），如果是不打印它。这可能会导致问题。您确定要检查的字符串是否在字符串向量中？

Check for the condition if it == strings.end(), if it is don't print it. This could cause the issue. Are you sure the string you're trying to check is in the vector of strings?

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