打印给定字符串中最长的名称

Question

我编写了以下程序来显示给定字符串中最长的名称，但输出与预期不符。

#include <iostream>
using namespace std;

int main() 
{
        
        int t;
        cin>>t;
        
        while(t--)
        {
       
            int n;
            cin>>n;
            
            string rr[n];
        
           for(int i=0;i<n;i++)
           {
             cin>>rr[i];
           }
                   
           string max = rr[0];
            for(int j=1;j<n;j++)
            {
              if(rr[j]>max)
              {
                 max=rr[j];
                
              }
            }
        
        cout<<"Longest name in the string is:"<<max<<endl;
        }
 
    return 0;
}

2 // no of test case
6 // no of elements in string
Harsh
Gaurav
GauravMiglani
HarshAgarwal
GeeksforGeeksGeeks
Programmiz


Longest name in the string is:Programmiz

Answer 1

可变长度数组，如本代码 sn-p

int n;
cin>>n;

string rr[n];

不是标准的 C++ 功能。相反，您应该使用标准容器std::vector<std::string>。

在这个if语句中

if(rr[j]>max)

你不是在比较字符串的长度。看来你的意思

if( rr[j].length() > max.length() )

变量t 和n 也应该有一个无符号整数类型，例如

unsigned int t = 0;
//...
unsigned int n = 0;

注意已经有标准算法std::max_element可以代替手动写循环使用。

例如

#include <iostream>
#include <string>
#include <vector>
#include <iterator>
#include <algorithm>

//...

std::vector<std::string> v( n );

//...

auto it = std::max_element( std::begin( v ), std::end( v ),
                            []( const auto &s1, const auto &s2 )
                            {
                                return s1.length() < s2.length();
                            } );
 
std::cout << "Longest name in the string is: " << *it << std::endl;

这是一个演示程序。

#include <iostream>
#include <string>
#include <vector>
#include <iterator>
#include <algorithm>

int main() 
{
    std::vector<std::string> v = 
    { 
        "one", "two", "three", "four", "vide", "six", "seven", "eight", "nine", "ten"
    };


    auto it = std::max_element( std::begin( v ), std::end( v ),
                            []( const auto &s1, const auto &s2 )
                            {
                                return s1.length() < s2.length();
                            } );
                            
    
    std::cout << "Longest name in the string is: " << *it << std::endl;
    
    return 0;
}

它的输出是

Longest name in the string is: three

即程序输出第一个最大长度的字符串。如果您需要找到具有最大长度的最后一个字符串，请使用反向迭代器，如下所示。

#include <iostream>
#include <string>
#include <vector>
#include <iterator>
#include <algorithm>

int main() 
{
    std::vector<std::string> v = 
    { 
        "one", "two", "three", "four", "vide", "six", "seven", "eight", "nine", "ten"
    };


    auto it = std::max_element( std::rbegin( v ), std::rend( v ),
                            []( const auto &s1, const auto &s2 )
                            {
                                return s1.length() < s2.length();
                            } );
                            
    
    std::cout << "Longest name in the string is: " << *it << std::endl;
    
    return 0;
}

现在程序输出是

Longest name in the string is: eight

Answer 2

试试这个代码！！ 在字符串中查找最小和最大的单词

// CPP Program to find Smallest and 
// Largest Word in a String 
#include<iostream> 
#include<cstring> 
using namespace std; 

void minMaxLengthWords(string input, string &minWord, string &maxWord) 
{ 
    // minWord and maxWord are received by reference 
    // and not by value 
    // will be used to store and return output 
    int len = input.length(); 
    int si = 0, ei = 0; 
    int min_length = len, min_start_index = 0, max_length = 0, max_start_index = 0; 

    // Loop while input string is not empty 
    while (ei <= len) 
    { 
        if (ei < len && input[ei] != ' ') 
            ei++; 
        
        else
        { 
            // end of a word 
            // find curr word length 
            int curr_length = ei - si; 
        
            if (curr_length < min_length) 
            { 
                min_length = curr_length; 
                min_start_index = si; 
            } 
            
            if (curr_length > max_length) 
            { 
                max_length = curr_length; 
                max_start_index = si; 
            } 
            ei++; 
            si = ei; 
        } 
    } 
    
    // store minimum and maximum length words 
    minWord = input.substr(min_start_index, min_length); 
    maxWord = input.substr(max_start_index, max_length); 
} 

// Driver code 
int main() 
{ 
    string a = "GeeksforGeeks A Computer Science portal for Geeks"; 
    string minWord, maxWord; 
    minMaxLengthWords(a, minWord, maxWord); 
    
    // to take input in string use getline(cin, a); 
    cout << "Minimum length word: "
        << minWord << endl 
        << "Maximum length word: "
        << maxWord << endl; 
}