I am very new to this and I am having a hard time grasping what I need to be doing. How do I read from a file and determine how many inputs are on a line so that I can do certain actions depending on how many inputs are available on the line?!

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- 10-24-2005megsb3uReading Input Files
I am very new to this and I am having a hard time grasping what I need to be doing. How do I read from a file and determine how many inputs are on a line so that I can do certain actions depending on how many inputs are available on the line?!

- 10-24-2005EnahsQuote:

How do I read from a file and determine how many inputs are on a line so that I can do certain actions depending on how many inputs are available on the line?!

Could you maybe give an example of what you are trying to do? (verbally) - 10-24-2005megsb3u
Each line of the file has either 1, 2, or 3 dimensions listed on it. If there is 1 dimesnsion, I need to calculate the area of a circle and square.......if 2 dimensions, I need to calculate the area of a rectangle, etc. I know how to do the calculations and output the calculations. I just do not know how to read the file and determine how many dimensions are on the line.

- 10-24-2005Enahs
This is one method:

Code:`#include <iostream>`

#include <fstream>

using namespace std;

int main()

{

ifstream file_in;

file_in.open("input.txt");

int _1;

int _2;

int _3;

char check;

file_in >> _1; //Goes first, we assume atleast one is there

check = file_in.peek(); //Looks at next char

if (check != '/n') //if next char is new line this if statement is skipped

{

file_in >> _2;

check = file_in.peek();

}

if (check != '/n') // If same as before but with 3rd char

{

file_in >> _3;

}

file_in.close();

cout << _1 << " " << _2 << " " << _3;

system("pause");

return 0;

}

Here is the input file:

Code:`1 2 3`

You will want to put it in a loop to get all the lines until end of file.

The peek and the instream ignore spaces, so it works perfect in this case. Each number can be separated by 10 spaces and it will still work the same.

This is not the only method, but fairly easily.

Hopefully it gets you started in the correction direction.

Peek:

http://www.cplusplus.com/ref/iostream/istream/peek.html

It also currently hardcodeed to output all three no matter what, so if you make a input file with just 2 it will have error in the output. - 10-24-2005megsb3u
Thank you!!! That helps immensely, it is just what I needed.