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.

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

Answer 1

The main idea is that you read the input line by line and process each line accordingly

Some information is missing like

what to do with test cases like
F=abc def,L=efg hij,V=1234

I have given a basic idea and you can modify accordingly

while (cin.getline(inputLine, 256, '\n'))
{
bool validString = true;
int n = strlen(inputLine);
if (n == 0)
continue;

{

cout << "The first Name stored in the array is: " ;

cout << it << endl;

}

// visualisation for the input string
// cout << n << endl ;
// for(int i = 0 ; i < n ; i++){
// cout << inputLine[i] ;
// }
// cout << endl ;
int i = 0;
string fname, lname;
int votes = 0;

while (i < n && isspace(inputLine[i]))
i++;
if (inputLine[i] == 'F')
{
i++ ;
while (i < n && isspace(inputLine[i]))
i++;
if (inputLine[i] != '=')
{
validString = false;
}
}
else
{
validString = false;
}
i++;

while (i < n && isspace(inputLine[i]))
i++;
int sp = i;
while (i < n && isalpha(inputLine[i]) && inputLine[i] != ',')
{
i++;
}
for (int j = sp; j < i; j++)
{
fname += inputLine[j];
}
// cout << fname << endl ;
if (validString)
{
firstName.push_back(fname);
}
  
}
for (auto it : firstName)
{
cout << "The first Name stored in the array is: " ;
cout << it << endl;
}
This is only for the first name
You can easily extend this for last name and votes.
Remeber to use stoi to store the number of votes as integers

Another advanced Idea is to store the position of commas in a vector and then if their number is greater than 2 you return invalid string
else copy the input string into 3 different segments

for(int i = 0 ; i < positionOfCommaInString[0] ; i++){
fname += inputLine[i] ;
}
for (int i = positionOfCommaInString[0] ; i < positionOfCommaInString[1] ; i++)
{
lname += inputLine[i];
}
for (int i = positionOfCommaInString[1] ; i < n ; i++)
{
votes += inputLine[i];
}
and don't put the character into string if isspace(inputLine[i]) return true

Construction for postitonOfCommaInString

int n = strlen(inputLine) ;
for(int i = 0 ; i < n ; i++){
if(inputLine[i] == ',') positionOfCommaInString.push_back(i) ;
}