我得到了一个 txt 文件，里面有单词和它们的定义，中间有分号和不同的空格，每个单词都在新行中有定义。看起来像这样：
我得到了一个代码，但我不知道如何从文件中读取然后按字母搜索。感谢您的帮助。
我得到了一个代码，但我不知道如何从文件中读取然后按字母搜索。感谢您的帮助。
#include <iostream>
#include <string>
#include <fstream>
using namespace std;
int main(){
ifstream input;
input.open("dictionary.txt");
if(!input.is_open()){
cout << "Error" << endl;
}
else{
char ch;
string str;
for (int i = 0; i < 3; i++){
cout << "Reading file";
cout << " " << i << endl;
sleep(0);
system("cls");
}
cout << "File was open" << endl;
sleep(0);
cout.flush();
system("cls");
int choise;
menu:
cout << "1. Starting\n2. Containing\n3. Ending\n4. Stop\nInput your choise: ";
cin >> choise;
system("cls");
switch(choise){
case 1:{ // searching by 1 letter
cout << "Input letter: "
goto menu;
}
case 2:{ // searching by any letter in word
goto menu;
}
case 3:{ // searching by last letter
goto menu;
}
case 4:{
system("cls");
cout << "Closing file" << endl;
sleep(2);
break;
}
default:{
cout << "Input 1-4!" << endl;
goto menu;
}
}
}
input.close();
}
答案 0 :(得分：1)
这是一个如何解决您的问题的示例。我已经编写了字符串搜索代码、字典元素加载代码并重写了删除 goto 的输入循环。代码还是有问题，比如只加载了字典的3个元素。
#include <iostream>
#include <string>
#include <fstream>
#include <unistd.h>
#include <vector>
using namespace std;
struct mydictionary
{
string sDefinition;
string sDescription;
};
void PrintByFirstLetter(const std::vector<mydictionary>& dict, char letter) {
for (auto &istr: dict) {
if( istr.sDefinition.length() && *istr.sDefinition.begin() == letter)
cout << istr.sDefinition << " - " << istr.sDescription << endl;
}
}
void PrintByLastLetter(const std::vector<mydictionary>& dict, char letter) {
for (auto &istr: dict) {
if( istr.sDefinition.length() && *(--istr.sDefinition.end()) == letter)
cout << istr.sDefinition << " - " << istr.sDescription << endl;
}
}
void PrintByAnyLetter(const std::vector<mydictionary>& dict, char letter) {
for (auto &istr: dict) {
//if (istr.sDefinition.find(letter) != istr.sDefinition.end())
if (istr.sDefinition.find(letter) != std::string::npos)
cout << istr.sDefinition << " - " << istr.sDescription << endl;
}
}
int main(){
ifstream input("dictionary.txt");
if(!input.is_open()) {
cout << "Failed to open dictionary" << endl;
}
else {
mydictionary mdc;
std::vector<mydictionary> dict;
for (int i = 0; i < 3; i++) {
cout << "Reading file";
cout << " " << i << endl;
std::getline(input, mdc.sDefinition, ';');
cout << mdc.sDefinition << endl;
std::getline(input, mdc.sDescription);
cout << mdc.sDescription << endl;
dict.push_back(mdc);
sleep(0);
system("cls");
}
cout << "File was open" << endl;
sleep(0);
cout.flush();
system("cls");
int choise;
do
{
cout << "1. Starting\n2. Containing\n3. Ending\n4. Stop\nInput your choise: ";
cin >> choise;
system("cls");
if(choise >= 1 && choise <= 3) {
char letter;
cout << "Input letter:";
cin >> letter;
if( choise == 1) // searching by 1 letter
PrintByFirstLetter(dict, letter);
else if( choise == 2) // searching by any letter in word
PrintByAnyLetter(dict, letter);
else if( choise == 3) // searching by last letter
PrintByLastLetter(dict, letter);
}
else if(choise == 4) {
system("cls");
cout << "Closing file" << endl;
sleep(2);
break;
}
else
cout << "Input 1-4!" << endl;
} while(1);
}
}
答案 1 :(得分：1)
您也可以使用正确的 C++ 代码来完成任务。
使用现代 C++ 元素和算法。
而且，尤其是通过真正使用所有 iostream 设施。
一个例子可能是：
#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <iomanip>
#include <iterator>
#include <algorithm>
#include <limits>
struct TermDefinition {
// The data
std::string term{};
std::string definition{};
// Override extractor operator
friend std::istream& operator >> (std::istream& is, TermDefinition& td) {
std::getline(std::getline(is, td.term, ';') >> std::ws, td.definition);
return is;
}
// Overwrite inserter operator
friend std::ostream& operator << (std::ostream& os, const TermDefinition& td) {
return os << td.term << " - " << td.definition;
}
};
int main() {
// Open file and check, if it could be opened
if (std::ifstream dictionaryStream{ "dictionary.txt" }; dictionaryStream) {
// Read complete file. Split it into components. Add to vector
std::vector dictionary(std::istream_iterator<TermDefinition>(dictionaryStream), {});
// As long as we should run the program, do the loop
bool runProgram{ true };
while (runProgram) {
// Get teh election for the user. Check for errors in input
std::cout << "\n\nMenu. Please select\n\n1 -> Starting\n2 -> Containing\n3 -> Ending\n4 -> Stop\n\nPlease enter 1 or 2 or 3 or 4: ";
if (unsigned int selection{}; std::cin >> selection) {
// Depending on selction gieven by user
switch (selection) {
case 1:
// Give instruction to user
std::cout << "\n\nSearching by first letter. Enter letter: ";
// Get one letter from user and check for valid input
if (std::string letter{}; std::getline(std::cin >> std::ws, letter) && letter.length() == 1)
// Copy all dictionary entries fullfilling the search criteria to std::cout
std::copy_if(dictionary.begin(), dictionary.end(), std::ostream_iterator<TermDefinition>(std::cout, "\n"),
[&letter](const TermDefinition& td) { return *td.term.begin() == letter[0]; });
break;
case 2:
// Give instruction to user
std::cout << "\n\nSearching by any letter. Enter letter: ";
// Get one letter from user and check for valid input
if (std::string letter{}; std::getline(std::cin >> std::ws, letter) && letter.length() == 1)
// Copy all dictionary entries fullfilling the search criteria to std::cout
std::copy_if(dictionary.begin(), dictionary.end(), std::ostream_iterator<TermDefinition>(std::cout, "\n"),
[&letter](const TermDefinition& td) { return td.term.find(letter[0]) != std::string::npos; });
break;
case 3:
// Give instruction to user
std::cout << "\n\nSearching by last letter. Enter letter: ";
// Get one letter from user and check for valid input
if (std::string letter{}; std::getline(std::cin >> std::ws, letter) && letter.length() == 1)
// Copy all dictionary entries fullfilling the search criteria to std::cout
std::copy_if(dictionary.begin(), dictionary.end(), std::ostream_iterator<TermDefinition>(std::cout, "\n"),
[&letter](const TermDefinition& td) { return td.term.back() == letter[0]; });
break;
case 4:
// User wants to stop the program
// Set loop flag to 0
runProgram = false;
std::cout << "\n\nDone. Exiting program . . .\n\n";
break;
default:
std::cout << "\n\nInvalid number. Please try again\n\n";
break;
}
}
else {
std::cout << "\n\nError: Invalid input. Please try again\n\n\n";
// Reset bad input state an consume nonesense characters
std::cin.clear();
std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
}
}
}
else std::cerr << "\n\nError: Could not open input file!\n\n";
return 0;
}
您已经接受了另一个答案。所以，我的猜测是你没有读过这篇文章，因此不需要进一步的解释。否则，请发表评论，我会添加说明。