Question

Checking Input File for correct line format.

So for my C++ assignment, my professor says we need to validate the Input File, if there are white lines and spaces, in which it will ignore them, separated by a comma, and that all data items are there. This will be used in a program where i will store these into an Array, and display them in First name, Last name, and Number of Votes vertical columned categories.

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 suppose to use.

void readFile(Candidate candidates[]) {

string line;

ifstream infile;

infile.open("elections.txt");

while (!infile.eof()) {

getline(infile,line);

// your code here

}

infile.close();

}

Answer 1

/************************************

c++ program

**************************************/

#include <iostream>
#include <fstream>
#include <string.h>
#include <vector>

using namespace std;

//class for Candidate
class Candidate {
private:
string firstName;
string lastName;
int numberOfVotes;
public:
  
Candidate(){
  
}
Candidate(string fName,string lName,int votes){
firstName = fName;
lastName = lName;
numberOfVotes = votes;
}
  
string getFirstName(){
return firstName;
}
  
string getLastName(){
return lastName;
}
  
int getNumberOfVotes(){
return numberOfVotes;
}
  
};

void readFile(Candidate candidates[]) {

string line;

ifstream infile;

infile.open("elections.txt");
  
int candidateCounter = 0;

while (!infile.eof()) {

getline(infile,line);
  
if(line.empty()){
continue;
}
  
//parse each line with respect to comma
  
  
char lineChars[line.length()];
int i;
  
//copy current linr string into char array
for(i = 0; i < sizeof(lineChars); i++){
lineChars[i] = line[i];
}
lineChars[i+1]= '\0'; //terminate the char array with end of string
  
char* lineToken = strtok(lineChars, ","); //start tokennize char array lineChars with comma
  
vector<string> lineVectors; //here we will put each token for this line which was separayed by comma
  
while(lineToken!=NULL) //continue as long as final token fr this line is not found
{
lineVectors.push_back(lineToken); //add the token
// cout<<lineToken<<endl;
lineToken = strtok(NULL,",");
}
  
vector<string> dataVectors;
for(int k = 0 ; k < lineVectors.size(); k++){
//for each lineVector get char array
string data = lineVectors[k];
  
char record[data.length()];
int j;
for(j = 0; j < sizeof(record); j++){
if(data[j]==' '){
j++;
}
record[j] = data[j];
}
  
record[j+1]='\0'; //charb array is formed from current string in linevector
  
  
//parse the char array with respect to "="
char* recordToken = strtok(record, "=");
int counter = 0;
while(recordToken!=NULL){
counter++;
//cout<<recordToken<<endl;
if(counter == 2){
dataVectors.push_back(recordToken); //put the right side tken of of =, into dataVector
}
recordToken = strtok(NULL,"=");
}
}//end of processing of each string in curent line vector
  
  
if(dataVectors.size()==3){ //if data vector has 3 items in it (first name, last name, numbr of votes)
int votes = stoi(dataVectors[2]); //convert vote from string to int
candidates[candidateCounter] = Candidate(dataVectors[0],dataVectors[1],votes);//add it to candidates array
candidateCounter++; //increase counter index
}

}

infile.close();

}

int main()
{
int numOfCandidates = 10;
Candidate candidates[numOfCandidates] = {};//create array of 10 candidates
  
readFile(candidates); //candidates array will be populated
  
for(int i = 0; i < 10 ;i ++){
Candidate c = candidates[i];
if(c.getFirstName().empty()){
continue;
}
//print data
cout<< c.getFirstName()<<" ; "<<c.getLastName()<<" ; "<< c.getNumberOfVotes()<<endl;
}
}

========================================

output

=========================================

Michael ; John ; 6522
Danny ; Red ; 2003
Hillary ; Clinton ; 1588
Albert ; Lee ; 5332
Roger ; Kane ; 3562

=========================

input file used

=========================

F=Michael,L=John,V=6522
F=Danny,L=Red,V=2003
F=Hillary,L=Clinton, V=1588
F=Albert,L=Lee,V=5332
F=Steven,L=JohnV=4429

F=Roger,L=Kane,V=3562