c++ - 比较文件中的字符串

Question

<分区>

Answer 1

使用嵌套循环可以达到您的预期；

#include <iostream>
#include <fstream>
#include <vector> //include this to use vector

using namespace std;

int main() {

    //to take input from the file
    ifstream fin;

    //to read the same strings into 2 arrays so we can loop it appropriately
    //by taking one string and comparing it to all below it.
    vector <string> line1;
    vector <string> line2;

    //to hold a line of string
    string temp;

    //replace this with with your file 
    fin.open("hello.txt");

    //to check if file cannot be opened or does not exist
    if(!fin.is_open()) {
        cout << "file could not be opened";
    }

    //strings are inserted into element of these 2 vectors 
    //(Internally, vectors use a dynamically allocated array to store their elements in adjacent memory locations)
    //that is why i decided to use vectors. Also, using the push_back method
    //to insert the strings into both arrays means we don't have to specify the size of the array
    while (getline(fin, temp)) {
        line1.push_back(temp);
        line2.push_back(temp);
    }


    //nested loop is used to make sure one string is used to operate 
    //on all the strings in the file and move to the next to do same
    //and so on...
    for (unsigned int i = 0; i < line1.size(); i++) {
        for (unsigned int j = 0; j < line2.size(); j++) {
            //you can compare first string with all below here however you want to do it
            //I just did this so you see how it behaves
            cout << line1[i] << " = " << line2[j] << endl;
        }
    }

    return 0;
}