asked on

file redirection

how do we read in a data file using redirection sign ie < so that we are able to pass the data in and use in the program. we want to be able to type

a.out < filename where a.out is the executable and filename is the text file
with data in it.

ASKER CERTIFIED SOLUTION

nietod

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nietod

If you are not familar with cin and/or stream objects, you need to include the file <iostream> which defines the input stream class "istream" and the "cin" object of this class. both of these names are defined in the "std" namespace, so you may wisht to include a "using namespace std;" line otherwise you will have to specify "std::" before these names.

You can read text from the input stream object using the getline() member function, but this is inconvenient if you don't know the length of the line to be read (you have to set an arbitaray limit.) so I prefer to use the global getline function which reads a line of any length into a string object, like

string CurLin

getline(cin,CurLin); // read a line.

let me know if you have any questions.

kkooty

ASKER

thanks that was usefull.

nietod

If you are "done" then you should grade the question. If not, no rush.

maxd128

Executing command
type filename | a.out
will pass text found in file "filename" to the standard input stream (like scanf or cin) of executable a.out