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Files
A File in V is an abstraction of any file object accessible by the program and is closely associated with os library.

Reading Files

Reading a file is an important task to tackle several different problems in computer science. In order to accomplish this task you can use the V native library os as described below:
import os
fn main() {
mut fp := flag.new_flag_parser(os.args)
generator := fp.string('generator', '', 'generator name')
method := fp.string('method', '', 'generator method name')
path := './data/$generator/$method'
if os.file_exists(path) {
print_generator_sample(path)
} else {
println('File does not exist')
return
}
}
fn print_generator_sample(path string) {
contents := os.read_file(path.trim_space()) or {
println('Failed to open $path')
return
}
lines := contents.split_into_lines()
length := lines.len
print_random_element(lines, length)
}
fn print_random_element(lines []string, length int) {
rand.seed(time.now().uni)
println(lines[rand.next(length-1)])
}

Writing files

Writing files in V is similar to read files.
import os
fn main() {
path := './data/file.txt'
text := 'Full text description.'
if contents := os.write_file(path, text) or {
println('Failed while creating file')
return
}
content_lines = read_file(path)
print(content_lines)
}
fn read_file(path string) {
contents := os.read_file(path.trim_space()) or {
println('Failed to open $path')
return
}
return contents.split_into_lines()
}

Exercises

  1. 1.
    Write a V program to create a new file with content.
  2. 2.
    Write a V program to read 2 different files and display their content.
  3. 3.
    Read how the os library works in V and understand how you could use it.
  4. 4.
    Encode a nested json string and write a new file with the result.
Last modified 2yr ago