Nim Files - read and write a file

This tutorial explains multiple examples of files.

How to read a file in Nim

Suppose, you have a file test.txt that contains the following content.

one
two
three

Let’s see an example to read file content.

The readFile() procedure reads the entire file content into a string variable.

try:
  let str = readFile("test.txt")
  echo str
except:
  console.log("Unable to read a file")

If the file is large, it is not good to read the entire file content into a string. It is better to read line by line.

Here is an example to read file line by line

create file stream using the open method
use the readLine() method to read file line by line
print the line
when you are done with file reading, you have to close the file stream using the defer and close method

try:
  let file = open("test.txt")
  defer: file.close()

  let line = file.readLine()
  echo line
except:
  console.log("Unable to read a file")

This is an example of writing a string into a file.

try:
let
  fileName = "/example/test.txt"
  str = "one two three"
writeFile(fileName, str)
except:
  console.log("Unable to write a file")