files.md

title
Files

A fast way to count number of lines

Some approaches to manipulating text file data

• readAll() to read all the file into a single string variable. Fast but not practical for enormous files. Use splitLines iterator to do line-based manipulations

• readLine() to read from file a line at a time

• CsvParse() with readRow() to perform line-based manipulation for rows of text that need to be broken into "fields".

import parsecsv

• memfiles and lines() iterator to iterate over memory mapped portions of the file (see example above).

Ensuring the file is closed

The defer() statement can be used instead of try: finally: blocks

  import strutils
  var   
    lineCnt = 0
    f = open("test_readfile2.nim")
  defer: close(f)
  for line in f.readAll().splitLines():
    inc lineCnt
  echo lineCnt