C++ lexicographical_compare用法及代码示例

C++ STL 提供了许多实用程序来解决基本的常见生活问题。比较值总是必要的，但有时我们也需要比较字符串。因此，本文旨在解释允许比较字符串的“lexicographical_compare()”。该函数在“algorithm”标头中定义。它有两个实现。语法1：lexicographical_compare(iter1 beg1, iter1 end1, iter2 beg2, iter2 end2)

Template:
template 
  bool lexicographical_compare(iter1 beg1, iter1 end1, iter2 beg2, iter2 end2)
Parameters : 
beg1 :  Input iterator to initial position of first sequence.
end1 :  Input iterator to final position of first sequence.

beg2 :  Input iterator to initial position of second sequence.
end2 :  Input iterator to final position of second sequence.

Return value : 
Returns a boolean true, if range1 is strictly lexicographically 
smaller than range2 else returns a false.

CPP


// C++ code to demonstrate the working of 
// lexicographical_compare()
#include<iostream>
#include<algorithm> // for lexicographical_compare()
using namespace std;
int main()
{
    // initializing char arrays
    char one[] = "geeksforgeeks";
    char two[] = "gfg";
     
    // using lexicographical_compare for checking 
    // is "one" is less than "two"
    if( lexicographical_compare(one, one+13, two, two+3))
    {
        cout << "geeksforgeeks is lexicographically less than gfg";
         
    }
    else
    {
        cout << "geeksforgeeks is not lexicographically less than gfg";
         
    }
     
}

时间复杂度：O(N)

空间复杂度：O(1)

输出：

geeksforgeeks is lexicographically less than gfg

语法 2： lexicographical_compare(iter1 beg1, iter1 end1, iter2 beg2, iter2 end2, 比较 comp)

Template:
template 
  bool lexicographical_compare(iter1 beg1, iter1 end1, iter2 beg2, iter2 end2)
Parameters : 
beg1 :  Input iterator to initial position of first sequence.
end1 :  Input iterator to final position of first sequence.

beg2 :  Input iterator to initial position of second sequence.
end2 :  Input iterator to final position of second sequence.

comp : The comparator function that returns a boolean
true/false of the each elements compared. This function 
accepts two arguments. This can be function pointer or 
function object and cannot change values.

Return value : 
Returns a boolean true, if range1 is strictly lexicographically smaller 
than range2 else returns a false.

CPP


// C++ code to demonstrate the working of 
// lexicographical_compare()
#include<iostream>
#include<algorithm> // for lexicographical_compare()
using namespace std;
// helper function to convert all into lower case:
bool comp (char s1, char s2)
{
    return tolower(s1)<tolower(s2);
}
int main()
{
    // initializing char arrays
    char one[] = "geeksforgeeks";
    char two[] = "Gfg";
     
    // using lexicographical_compare for checking 
    // is "one" is less than "two"
    // returns false as "g" has larger ASCII value than "G"
    if( lexicographical_compare(one, one+13, two, two+3))
    {
        cout << "geeksforgeeks is lexicographically less than Gfg\n";
         
    }
    else
    {
        cout << "geeksforgeeks is not lexicographically less than Gfg\n";
         
    }
     
    // using lexicographical_compare for checking 
    // is "one" is less than "two"
    // returns true this time as all converted into lowercase
    if( lexicographical_compare(one, one+13, two, two+3, comp))
    {
        cout << "geeksforgeeks is lexicographically less  ";
        cout << "than Gfg( case-insensitive )";
         
    }
    else
    {
        cout << "geeksforgeeks is not lexicographically less ";
        cout<< "than Gfg( case-insensitive )";
         
    }
     
}

时间复杂度：O(N)

空间复杂度：O(1)

输出：

geeksforgeeks is not lexicographically less than Gfg
geeksforgeeks is lexicographically less than Gfg( case-insensitive )

可能的应用：比较字符串一般可以用在字典中，我们需要按照字典顺序放置单词。例如，在给定的单词集中查找字典中第一个出现的单词。

CPP


// C++ code to demonstrate the application of 
// lexicographical_compare()
#include<bits/stdc++.h>
using namespace std;
int main()
{
    // initializing char arrays
    char list[][100]={
        {'a','b','a','c','u','s'},
        {'a','p','p','l','e'},
        {'c','a','r'},
        {'a','b','b','a'}
    };
     
    char min[100] = "zzzzzz";
     
    // using lexicographical_compare for checking 
    // the smallest
    for (int i=0; i<4; i++)
    { 
        if( lexicographical_compare(list[i], list[i] 
        + strlen(list[i]), min, min+strlen(min)))
    {
        strcpy(min,list[i]);
    }
    }
     
    // prints "abacus"
    cout << "The smallest string is : ";
    for(int i = 0; min[i]!='&#092;&#048;'; i++)
    {
        cout<<min[i];
    }
     
     
}

时间复杂度：O(N)

空间复杂度：O(1)

输出：

The smallest string is : abacus

相关用法

注：本文由纯净天空筛选整理自佚名大神的英文原创作品 lexicographical_compare in C++。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。