[英]C++ program crashes when trying to sort a vector of strings
I'm trying to sort an array of strings in C++, but I am getting the following error message:我正在尝试在 C++ 中对字符串数组进行排序,但收到以下错误消息:
terminate called after throwing an instance of 'std::logic_error' what(): basic_string::_M_construct null not valid
The following program causes the previous error.以下程序会导致上一个错误。 I got the error when
v
has 17 elements, but everything works fine when v
has less elements.我得到的错误时,
v
有17个元素,但一切正常时, v
具有更少的元件。
Could someone point me out what is the problem?有人能指出我有什么问题吗? I'm using gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)
我正在使用gcc 版本 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)
#include <vector>
#include <string>
#include <algorithm>
using namespace std;
bool comp (string s1, string s2) {
if (s1.size() < s2.size())
return false;
else
return true;
}
int main () {
vector<string> v = { "a", "a", "a", "a",
"a", "a", "a", "a",
"a", "a", "a", "a",
"a", "a", "a", "a",
"a" };
sort(v.begin(), v.end(), comp);
return 0;
}
The comparator you pass to sort must satisfy the named requirement Compare :您传递给 sort 的比较器必须满足命名要求 Compare :
Establishes strict weak ordering relation with the following properties
与以下属性建立严格的弱排序关系
For all a, comp(a,a)==false If comp(a,b)==true then comp(b,a)==false if comp(a,b)==true and comp(b,c)==true then comp(a,c)==true
With your comparator: comp(a,a) == true
.使用比较器:
comp(a,a) == true
。 As you do not fullfill the preconditions of std::sort
your code has undefined behavior.由于您没有满足
std::sort
的先决条件,因此您的代码具有未定义的行为。
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