Question

Validating Input file,

So for my C++ assignment, my professor says we need to validate the Input File, Which means, if the line is missing a comma, one of the 3 information, or the string is a white line, it will ignore it. If the line has a white line, the program will correct it and will read in the line.

I will store these into an Array, and display them in First name, Last name, and Number of Votes vertical columned categories.

Apparently I skipped this part of the lecture and book, since he won't tell me exactly and keeps telling me to read the book. But the book shows me how to make arrays, take a file and put it into an array. He said using substr and find() or something like that.

This is a sample of the txt file. My question is, What do i use to be able to take only the names and number and place them into an array. Please explain what each line is doing, even it is not completely obvious. I am a complete beginner.

F=Michael,L=John,V=3342

F=Danny,L=Red,V=2003

F=Hillary,L=Clinton, V=1588

F=Albert,L=Lee,V=5332

F=Steven,L=JohnV=4429

Correct line for the reference: F=John,L=Smith,V=3342

The line errors that your program needs to detect, are as follows:

incorrect token / separator, example in line 5: F=Steven,L=JohnV=4429

(comma missing) – lines with this error need to be ignored

space in token, example in line 3: F=Hillary,X=Clinton, V=1622

lines with this error need to be read, error fixed, data included in your dataset

empty line, example in line 6 – empty lines need to be ignored

This is the sample of the getline code we are HAVE to USE and FOLLOW.

void readFile(Candidate candidates[]) {

string line;

ifstream infile;

infile.open("elections.txt");

while (!infile.eof()) {

getline(infile,line);

// your code here

}

infile.close();

}

I DO NOT NEED A WHOLE CODE, JUST THE FUNCTION EXPLAINED WHAT THE FUNCTION AND THE CODE IS DOING BY LINE.

Answer 1

#######################################
       elections.txt
#######################################
F=Michael,L=John,V=3342
F=Danny,L=Red,V=2003
F=Hillary,L=Clinton, V=1588
F=Albert,L=Lee,V=5332
F=Steven,L=JohnV=4429



#######################################
            main.cpp
#######################################
#include <iostream>
#include <fstream>
#include <vector>
#include <sstream>
#include <cstring>

using namespace std;

// trim a string, it removes any spaces at end and start of the string
string trim(string& str) {
    str.erase(0, str.find_first_not_of(' '));       //prefixing spaces
    str.erase(str.find_last_not_of(' ')+1);         //surfixing spaces
    return str;
}

// this method counts the occurrences of a character in string.
int countCharacter(string s, char c) {  
        int count = 0;

        for (int i = 0; i < s.size(); i++) {
                if (s[i] == c) {
                        count++;
                }
        }

        return count;
}

// this method converts a comma separated string to tokens
// it returns all tokens in form of a vector
vector<string> tokens(string s) {
        vector<string> result;

        // while string has a comma
        while(s.find(",") != string::npos) {
                // find index of comma in string
                int index = s.find(",");
                
                // break token till comma
                string token = s.substr(0, index);
                
                // remove the token from original string
                s = s.substr(index + 1);

                // remove space from start of token, and push to vector of tokens
                result.push_back(trim(token));
        }

        // if last token is now not empty, push that too on vector
        if(!s.empty()) {
                result.push_back(trim(s));
        }

        return result;
}

// this method parses the token which is in format:
// F=<firstName>
// L=<lastName>
// V=<Votes>
void parseToken(string s) {
        if(s[0] == 'F') {
                cout << "FirstName: " << s.substr(2) << endl;
        } else if(s[0] == 'L') {
                cout << "LastName: " << s.substr(2) << endl;
        } else if(s[0] == 'V') {
                cout << "Votes: " << s.substr(2) << endl;
        } 
}

// method to read the file and print the votes
void readFile() {

        // variable to read the line
        string line;

        // File variable to read input file
        ifstream infile;

        // open the file to read
        infile.open("elections.txt");

        // while input file has lines
        while (!infile.eof()) {

                // read a line from the file
                getline(infile,line);

                // Here comes the main logic to parse the line
                int commaCount = countCharacter(line, ',');

                if(commaCount != 2) {
                        // Ignore line,
                        cout << "Incorrect token separator: " << line << endl;
                } else if(line.empty()) {
                        // ignore empty line.
                } else {
                        // We now have a line which does contain correct commas
                        // and is not empty line.
                        for(string t: tokens(line)) {
                                parseToken(t);
                        }
                }
                cout << endl;
        }

        // close the file we opened
        infile.close();

}

int main() {
        readFile();
}

**************************************************

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