C++中字符串到字符的转换

Question

我正在尝试使用 Hash Table 构建一个拼写检查验证器。我在文本文件中有单词列表。我想将它们导入程序并使用单独的链接将它们输入到 Hash Table 中。现在，我想运行程序，但我有这两个错误。谁能帮我解决这个问题？

at line 30-- no matching function for call to 'std::__cxx11::basic_string::push_back(std::__cxx11::string&)'

at line 40-- no match for 'operator==' (operand types are '__gnu_cxx::__alloc_traits, char>::value_type' {aka 'char'} and 'std::__cxx11::string' {aka 'std::__cxx11::basic_string'})

我知道将 str 转换为 char 是一个简单的错误，但我不知道如何在不更改程序其余部分的情况下进行操作。

我想要一个不改变现有代码的简单解决方案。如果不可能，请告诉我如何进行。

#include<iostream>
#include <string>
#include <cstring>
#include <fstream>


std::string hashTable[27];
int hashTableSize = 27;
#define MAX_LEN 27
using namespace std;


int hashFunc(std::string s)
{
    // A simple hashing, no collision handled
    int sum=0,index=0;
    for(std::string::size_type i=0; i < s.length(); i++)
    {
        sum += s[i];
    }
    index = sum % MAX_LEN;
    return index;
}

void insert(std::string s)
{
    // Compute the index using Hash Function
    int index = hashFunc(s);
    // Insert the element in the linked list at the particular index
    hashTable[index].push_back(s);
    }

void search(string s)
{
    //Compute the index by using the hash function
    int index = hashFunc(s);
    //Search the linked list at that specific index
    for(int i = 0;i < hashTable[index].size();i++)
    {
        if(hashTable[index][i] == s)
        {
            cout << s << " is found!" << endl;
            return;
        }
    }
    cout << s << " is not found!" << endl;
}
int main(){


    //opening text file
    std::ifstream inFile;
    inFile.open("un.txt");

    // If text file doesnot exist or not included in root folder.
    if(inFile.fail()) {

        std::cerr << "Error opening file"<< std::endl ;

        exit(1);
    }

    //if text file exists.
    std::string wordsinfile;
    std::string words[100];
    int count=0,i=0;
    std::string str;


    // writing words from text file into Array.
    while( !inFile.eof()) {
        inFile >> wordsinfile;
        words[i]=wordsinfile;
        count++;
        i++;
    }

    for (i=0;i<100;i++){
        std::cout<< words[i]<<std::endl;
    }


    for(i=0;i<=23;i++) {
        insert(words[i]);
    }


    int choice;
    string z;
    string y;
    while(1) {

        cout << "Enter choice. 1) Insert\n 2) Search\n 3) Exit\n";
        cin >> choice;
        switch (choice) {
            case 1:
                cin>>y;
                insert(y);
                break;
            case 2:

                cin>>z;
                search(z);
                break;
            case 3:
                exit(0);
        }
    }
    return 0;
}

我的 txt 文件有 38 个不同的单词，散列的大小 table 是 27

Answer 1

这是您程序的正确版本。您的哈希表应该是字符串的集合，并且由于您在搜索函数中使用索引，因此对哈希表使用 STL 向量应该可以解决问题。

#include <iostream>
#include <string>
#include <cstring>
#include <fstream>
#include <vector>

std::vector<std::string> hashTable[27];
int hashTableSize = 27;
#define MAX_LEN 27
using namespace std;


int hashFunc(std::string s)
{
    // A simple hashing, no collision handled
    int sum=0,index=0;
    for(std::string::size_type i=0; i < s.length(); i++)
    {
        sum += s[i];
    }
    index = sum % MAX_LEN;
    return index;
}

void insert(std::string s)
{
    // Compute the index using Hash Function
    int index = hashFunc(s);
    // Insert the element in the linked list at the particular index
    hashTable[index].push_back(s);
    }

void search(string s)
{
    //Compute the index by using the hash function
    int index = hashFunc(s);
    //Search the linked list at that specific index
    for(int i = 0;i < hashTable[index].size();i++)
    {
        if(hashTable[index][i] == s)
        {
            cout << s << " is found!" << endl;
            return;
        }
    }
    cout << s << " is not found!" << endl;
}

int main(){
    //opening text file
    std::ifstream inFile;
    inFile.open("un.txt");

    // If text file doesnot exist or not included in root folder.
    if(inFile.fail()) {

        std::cerr << "Error opening file"<< std::endl ;

        exit(1);
    }

    //if text file exists.
    std::string wordsinfile;
    std::vector<std::string> words;
    std::string str;


    // writing words from text file into Array.
    while( inFile >> wordsinfile) {
        words.push_back(std::move(wordsinfile));
    }

    std::cout << "Total words read: " << words.size() << std::endl;

    for (int i = 0;i < words.size(); i++){
        std::cout << words[i] << std::endl;
    }


    for(int i=0; i < words.size(); i++) {
        insert(words[i]);
    }


    int choice;
    string z;
    string y;
    while(1) {

        cout << "Enter choice. 1) Insert\n 2) Search\n 3) Exit\n";
        cin >> choice;
        switch (choice) {
            case 1:
                cin>>y;
                insert(y);
                break;
            case 2:

                cin>>z;
                search(z);
                break;
            case 3:
                exit(0);
        }
    }
    return 0;
}

C++中字符串到字符的转换

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