尝试对字符串向量进行排序时,C ++程序崩溃 [英] C++ program crashes when trying to sort a vector of strings
问题描述
我正在尝试对C ++中的字符串数组进行排序,但是却收到以下错误消息:
I'm trying to sort an array of strings in C++, but I am getting the following error message:
terminate called after throwing an instance of 'std::logic_error'
what(): basic_string::_M_construct null not valid
以下程序导致上一个错误.当 v
具有17个元素时出现错误,但是当 v
具有较少元素时,一切正常.
The following program causes the previous error. I got the error when v
has 17 elements, but everything works fine when v
has less elements.
有人可以指出我的问题吗?我正在使用 gcc版本7.5.0(Ubuntu 7.5.0-3ubuntu1〜18.04)
Could someone point me out what is the problem? I'm using gcc version 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;
}
推荐答案
传递给您的比较器必须满足命名需求比较:
The comparator you pass to sort must satisfy the named requirement Compare:
与以下项建立严格的弱排序关系属性
Establishes strict weak ordering relation with the following properties
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
使用您的比较器: comp(a,a)== true
.由于您没有完全满足 std :: sort
的前提条件,因此您的代码具有未定义的行为.
With your comparator: comp(a,a) == true
. As you do not fullfill the preconditions of std::sort
your code has undefined behavior.
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