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Array and File Help

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Join Date: Oct 2005

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Laughs Galore Laughs Galore is offline

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Array and File Help

Feb 25th, 2007

I am writing this program that reads in lines from a txt file into an array. Some lines start with a number and some don't. Problem is that I need help on how to display the lines that don't start with a number.

Examples of txt file:

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C++ Syntax (Toggle Plain Text)

Students
3 Girls
4 Boys

Code I have so far:

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getline(inFile,row); //read each line in file
 
while(!inFile.eof())
{
 
          list[count] = row; //store each line in array
 
          count ++;
 
         getline(inFile,row);
 
}
getline(inFile,row); //read each line in file

while(!inFile.eof())
{
         
          list[count] = row; //store each line in array
 
          count ++;
          
         getline(inFile,row);
         
}

I just don't know how to get each line that doesn't start with a number from the array and display it.

I have tried something like the below, but I think that it doesn't work since each line that has a number, stores whatever follows that number.

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for (i = 0; i < num; i++)
{
    if(list[i] != "3")
    {
    cout << i << ":" << list[i]<<endl;
    }
}
for (i = 0; i < num; i++)
{
    if(list[i] != "3")
    {
    cout << i << ":" << list[i]<<endl;
    }
}

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John A

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Re: Array and File Help

Feb 25th, 2007

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Originally Posted by Laughs Galore

I have tried something like the below, but I think that it doesn't work since each line that has a number, stores whatever follows that number.
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C++ Syntax (Toggle Plain Text)
for (i = 0; i < num; i++)
{
    if(list[i] != "3")
    {
    cout << i << ":" << list[i]<<endl;
    }
}
for (i = 0; i < num; i++) { if(list[i] != "3") { cout << i << ":" << list[i]<<endl; } }

I don't quite get why that would work even if all the lines have numbers, because getline() retrieves the full line, including the text after the number in your case. Comparing that entire line with a single number isn't going to work, whether the line has a number in front of it or not.

To print out all the lines, I'd suggest a simple loop:

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for (int i=0; i<num; i++)
    cout << i << ":" << list[i] << endl;
for (int i=0; i<num; i++)
    cout << i << ":" << list[i] << endl;

Now all you need to do is remove line numbers on the lines that do happen to have numbers.

For removing the number, I'd suggest using string::find_first_not_of with a single space as an argument. Now check that the character found is not a number with isalpha, and then you can proceed either by removing the number if it is one, or simply leaving the string as-is.

Or did I totally misunderstand what you're trying to do?

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