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 to use find(), so please explain how to use find().*

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

If you have any doubts, please give me comment...

find() : It will find the position of a given character for the given string.

substr(): It will extract string from start index to end index.

By using find, we will find comma indexes in the line. Then we will extract it and then we will print data.

readFile function will read the line by line and validating line, if it is ok, then It will assign into a structure array.

Code:

#include <iostream>

#include <fstream>

#include <sstream>

#include <string>

using namespace std;

#define MAX_SIZE 20

struct Candidate {

string fname;

string lname;

int votes;

};

string ltrim(string str){

int i=0;

while(str[i]==' ')

i++;

str = str.substr(i);

return str;

}

int readFile(Candidate candidates[]) {

string line;

ifstream infile;

infile.open("elections.txt");

string fname, lname, votes;

int n = 0;

while (!infile.eof()) {

getline(infile, line);

if(line!=""){

int comma1 = line.find(",");

if(comma1!=string::npos){

int comma2 = line.find(",", comma1+1);

if(comma2!=string::npos){

fname = ltrim(line.substr(0, comma1));

lname = ltrim(line.substr(comma1+1, comma2-comma1-1));

votes = ltrim(line.substr(comma2+1));

candidates[n].fname = fname.substr(2);

candidates[n].lname = lname.substr(2);

candidates[n].votes = stoi(votes.substr(2));

n++;

}

}

}

}

infile.close();

return n;

}

int main(){

Candidate candidates[MAX_SIZE];

int n = readFile(candidates);

cout<<"FName\tLName\tVotes"<<endl;

cout<<"-----------------------------"<<endl;

for(int i=0; i<n; i++){

cout<<candidates[i].fname<<"\t"<<candidates[i].lname<<"\t"<<candidates[i].votes<<endl;

}

}