The reset procedure associates a file variable with a file (i.e. opens the file variable and allows it to be used to manipulate the file). The reset procedure opens the file variable in read-only mode. The open procedure can also be used to open file variables in read-only mode.
File variables can get named in the following ways:
The program below is used to count the number of vowels and the total number of characters in the input file. If you run this program and don't supply a program argument like
then the program reads from the standad input file. If you run this program with a program argument like
ivm vowels filename
then the program will open the file named filename and read from it.
program vowels(f, output); var f : file of char; tot, vow : integer; c : char; begin reset(f); //Open the input file in readmode. tot := 0; //Initialize total number of chars read so far vow := 0; //Initialize total number of vowels read so far while not eof(f) do begin read(f, c); //Read character case c of 'a', 'e', 'i', 'o', 'u', 'A', 'E', 'I', 'O', 'U' : vow := vow + 1; otherwise //include "otherwise" so that non-vowels don't cause errors. end; tot := tot + 1; end; writeln('Total characters read = ', tot); writeln('Vowels read = ', vow) end.
Operating Systems: All Standard Pascal: Yes