Line Count Programming Challenge

[aurimas13]

I have a problem of figuring out what I am asked to do and how to start. The problem is this:

Here's a simple help free challenge to get you started: write a program that takes a file as an argument and counts the total number of lines. Lines are defined as ending with a newline character. Program usage should be

count filename.txt
and the output should be the line count.

How do you take a file as an argument?

Thank you.

[Naughty Albatross]

Hi,
> How do you take a file as an argument?

For example :

void readCountFile(std::string filename)
{
   // Your code...
}

And in your function main(), you call that function :
readCountFile("input.txt");

[Naughty Albatross]

Does that help? :)

[aurimas13]

Thank you, but I still remain confused.

[Arslan7041]

write a program that takes a file as an argument

If you mean taking a file name as a command line argument, then that would be like this:

int main(int argc, char* argv[])
{
    if(argc < 2) // checking to see if 2 arguments were passed from command line
    {
        cout << "TOO FEW ARGUMENTS\n";
        return 0;
    }

    ifstream file(argv[1]); // delcare and open file

    if(!file) // check if file opened
    {
        cout << "FILE NOT OPENED";
        return 0;
    }

When you run this on the command line, you'll have to pass in the file name as a command line argument. This will result in a total of 2 arguments passed in as the name of the program will automatically be inserted as the first argument (hence why we check for 2 arguments and argv[1] is the file name, because argv[0] is the program name).

[TheIdeasMan]

@closed account 5a8Ym39o6 (300)
> Does that help? :)

No, you missed the point.

@aurimas13

Program usage should be

count filename.txt

Your teacher means this:

int main(int argc, char *argv[]) {

http://en.cppreference.com/w/cpp/language/main_function

argc is the count of how arguments there were - you can use this to check for correct usage.

argv[0] is the program name - "count"

argv[1] is the first argument - the "filename.txt" Note that this is a char array, not a std::string

Good Luck !!

[48T7M4Gy]

A parameter is a variable in a method definition. When a method is called, the arguments are the data you pass into the method's parameters.

http://stackoverflow.com/questions/156767/whats-the-difference-between-an-argument-and-a-parameter

[aurimas13]

Thank you guys. I'm still a bit confused. Ok, so I have int main(int argc, char *argv[], but what should I do with this? I'm a novice. so can please anyone explain in simple terms what take a file as an argument mean and what steps I need to do? I can't grasp how to take a file as an argument and then later count the total number of lines. Does this assignment include ifstream?

[TheIdeasMan]

Start out with Arslan's code.

Did you understand this part is from the command line?

count filename.txt

have you heard of the function std::getline ?

http://www.cplusplus.com/reference/istream/basic_istream/getline/

You can put that in a loop.

Alternatively, for a less desirable C approach, count the number of newlines.

[aurimas13]

Did you understand this part is from the command line?

what is command line? I'm confused.

have you heard of the function std::getline ?

Yes.

You can put that in a loop.

Put getline in a loop? What that supposed to mean?

[Naughty Albatross]

> What is command line? I'm confused.
If all your answers are "I am confused", I would recommend you take this easier approach. And I am sure your professor won't scold badly at you I think :)

> Hi,
>> How do you take a file as an argument?

> For example :

void readCountFile(std::string filename)
{
   // Your code...
}

> And in your function main(), you call that function :
readCountFile("input.txt");

Give me several minutes. I will give you some details later.

[TheIdeasMan]

what is command line? I'm confused.

Once you have your program compiled, type this in the DOS prompt:

count filename.txt

Put getline in a loop? What that supposed to mean?

Inside the body (between the braces { } ) of a while loop.

http://www.cplusplus.com/doc/tutorial/

[aurimas13]

Thank you @closed account. I will look forward to you response.
By the way what you mean take an easier approach to this assignment? Thanks.

[Naughty Albatross]

@aurimas13
Before that, can you prepare an input file with some random text (about several lines)? Then show the content of the file (even its file name) to us.

[TheIdeasMan]

@aurimas13

closed account 5a8Ym39o6 (300) wrote:

If all your answers are "I am confused", I would recommend you take this easier approach. And I am sure your professor won't scold badly at you I think :)

I think you will loose plenty of points for not doing what the assignment says.

[Naughty Albatross]

@TheIdeasMan
A student should be at least aware of all small concepts before an assignment. Why would a professor force a student to solve such an assignment whereas the student doesn't even know (or has ever learned) what a "command line" is?

[aurimas13]

@closed account

To prepare an input file, should I simply use text editor, input words in the file and save as a .txt file?

[Naughty Albatross]

> To prepare an input file, should I simply use text editor, input words in the file and save as a .txt file?
Yes. You don't have to do this anymore :)

[Naughty Albatross]

Here is an example for you to get started. Try compling it && run it :

#include <iostream>
#include <string>
#include <fstream>

using namespace std;
void readCountFile(string filename)
{
    ifstream inFile(filename);

    if(!inFile.is_open())
    {
        cout << "Error : File " << filename << " not found" << endl;
        return;
    }

    string t;
    int lineCount = 0;
    while(getline(inFile, t)) lineCount += 1;

    cout << "The file '" << filename << "' has " << lineCount << " line(s)." << endl;
    inFile.close();
}

int main()
{
    readCountFile("input.txt");
    return 0;
}

And here is the content of the file input.txt (example) :

hello
this is my
david beccam is a daddy
mother mommy is mythy self
great
say bye
good nine :)

[Naughty Albatross]

Does that help? :)