从文件中读取一个单词

Question

我是 C++ 新手，我需要在文本文件“input.txt”中找到输入的单词 (searchWord)。

我现在有了它，它将输出文件中的每个单词，但我需要它来输出输入的字符串并找到它。

#include<iomanip>
#include<fstream>
#include<string>
using namespace std;

int main(){
    // Variable Declaration
    string fileName;
    string searchWord;
    int exitValue = 0;

    // Name the file to open
    ifstream inputFile;

    // Prompt the user to enter the file name
    cout << "Enter the name of the file: ";
    cin >> fileName;

    // Logic to determine if the file name equals "input.txt"
    if (fileName == "input.txt"){ // if user input = input.txt
        inputFile.open("input.txt"); // opening input.txt
    }
    else{
        cout << "\nCould not open '" << fileName << "'." << endl;
        exit(0);
    }

    // Prompt the user for a word to search for in the file
    cout << "Enter a value to search for: ";
    cin >> searchWord;

    // Logic to determine if the inputted string is in the file or not
    while (inputFile >> searchWord){
        cout << "\n'" << searchWord << "' was found in '" 
            << fileName << "'." << endl;
    }

    inputFile.close();
    return 0;
}

Answer 1

稍微有点不同：

// Logic to determine if the inputted string is in the file or not
string inputWord;
while (inputFile >> inputWord){ // Do not overwrite the given searchWord
    if(inputWord == searchWord ) { // Check if the input read equals searchWord     
        cout << "\n'" << searchWord << "' was found in '" 
             << fileName << "'." << endl;
        break; // End the loop
    }
}

Answer 2

这对我有用：

#include <cstdio>
#include <iostream>
#include <string>

using namespace std;

// Returns the index of the value you are looking for.
// If the value isn't found, it returns -1.
int searchFile(string filename, string value) {
    FILE *fp;
    int c, i = 0;
    string contents = "";

    fp = fopen(filename.c_str(), "r");
    while (true) {
        c = fgetc(fp);
        contents += c;
        if (feof(fp)) { 
            break;
        }

        i++;
        if (i >= value.length() && contents.substr(i - value.length(), i) == value) {
            return i;
        }
    }
    fclose(fp);
    return -1;  // value not found in file
}

int main() {
    string fileName;
    string value;
    cout << "Enter file name: ";
    cin >> fileName;
    cout << endl << "Enter search value: ";
    cin >> value;

    int index = searchFile(fileName.c_str(), value.c_str());
    if (index == -1) cout << "Not found";
    else cout << "Found at index " << index << endl;
    cin.get();
    cin.get();
    return 0;
}

从文件中读取一个单词

Reading in one word from a file

c++

readfile

c++17