Operation on file:

We concentrate first on the fgetl function that reads strings from the file one line at a time. The fgetl functions afford more control over how the data is read than the other input functions. The fgetl function reads one line of data from a file into the string; string functions can be used then to manipulate the data. As fgetl reads only one line, it generally is placed in a loop which keeps going until the end of the file is reached. The function feof returns the logical true if the end of the file has been reached. The function call feof(fid) would return the logical true when the end of the file has been reached for the file specified by fid, or logical false when not. A common algorithm for reading from a file into strings would be as shown below:

•  Try to open the file; check to make sure that the file open was successful.
•  If opened, the loop until end of the file is reached. For each of line in the file,

-  read it into the string

- manipulate the data

•  Try to close the file; check to make sure that the file close was successful.