STLalgorithm算法lexicographical_compare(30)
lexicographical_compare原型:
std::lexicographical_compare
default (1) |
template <class InputIterator1, class InputIterator2> bool lexicographical_compare (InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2); |
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custom (2) |
template <class InputIterator1, class InputIterator2, class Compare> bool lexicographical_compare (InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, Compare comp); |
该函数是按照字典序测试[frist1,last1)是否小于[first2,last2).
字典序是指按照字母在字典中出现的顺序。
该函数使用opeartor<或者是comp进行比较。
如果两个序列长度不同,并且短序列和长序列头部完全一样,例如example和examplee.那么,长度大的字典序比短序的大。
其行为类似于:
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一个简单的例子:
#include <iostream> #include <vector> #include <algorithm> using namespace std; int main(int argv,char **argc) { vector<char> v1{'h','e','l','l','o'}; vector<char> v2{'h','e','l','l','o','o'}; vector<char> v3{'h','e','l','m','o'}; cout<<"v1="; for(char i:v1) cout<<i<<" "; cout<<endl; cout<<"v2="; for(char i:v2) cout<<i<<" "; cout<<endl; cout<<"v3="; for(char i:v3) cout<<i<<" "; cout<<endl; if(lexicographical_compare(v1.begin(),v1.end(),v2.begin(),v2.end())) cout<<"v1 is less than v2 "<<endl; else cout<<"v2 is less than v1 "<<endl; if(lexicographical_compare(v1.begin(),v1.end(),v3.begin(),v3.end())) cout<<"v1 is less than v3 "<<endl; else cout<<"v3 is less than v1 "<<endl; }
运行截图:
该函数是否只能比较字母呢?答案是肯定的,不是!
因为对于任意的可以使用opeartor<进行比较的对象都可以使用该函数!
一个简单的例子:
#include <iostream> #include <vector> #include <algorithm> using namespace std; int main(int argv,char **argc) { vector<int> v1{1,2,3,4}; vector<int> v2{1,2,3,4,5}; vector<int> v3{1,2,3,3}; cout<<"v1="; for(int i:v1) cout<<i<<" "; cout<<endl; cout<<"v2="; for(int i:v2) cout<<i<<" "; cout<<endl; cout<<"v3="; for(int i:v3) cout<<i<<" "; cout<<endl; if(lexicographical_compare(v1.begin(),v1.end(),v2.begin(),v2.end())) cout<<"v1 is less than v2 "<<endl; else cout<<"v2 is less than v1 "<<endl; if(lexicographical_compare(v1.begin(),v1.end(),v3.begin(),v3.end())) cout<<"v1 is less than v3 "<<endl; else cout<<"v3 is less than v1 "<<endl; }
运行截图:
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author:天下无双
Email:coderguang@gmail.com
2014-9-17
于GDUT
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