Application Programming: Files and Input/Output

Q Format Code

Available Format Codes

The Q format code returns the number of characters in the input record remaining to be transferred during the current read operation. It is ignored during output formatting.

The syntax is:

q  

Format Q is useful for determining how many characters have been read on a line. For example, the following IDL statements count the number of characters in file demo.dat:

;Open file for reading.  
OPENR, 1, "demo.dat"  
  
;Create a longword integer to keep the count.  
N = 0L  
  
;Count the characters.  
WHILE(~ EOF(1)) DO BEGIN  
  READF, 1, CUR, FORMAT = '(q)' & N = N + CUR   
ENDWHILE  
  
;Report the result.  
PRINT, FORMAT = '("counted", N, "characters.")'  
  
;Close file.  
CLOSE, 1