Reading and writing to files

Reading and writing to files

A collection of one handy snippets for reading, manipulating and writing data to files in one line.

• Given a file with a single number on each line, reach only the first 10 lines, sum the total and print each number read.

module read_and_sum;

import std.conv : to;
import std.stdio: writeln;
import std.range : takeExactly, tee;
import std.algorithm.iteration : map, each;

void main()
{
    double total = 0;
    File("./10numbers.txt")
         // lazily iterate by line
        .byLine

         // pick first 10 lines
        .takeExactly(10)
         
         // convert each to double
        .map!(to!double)

         // add element ro total
        .tee!((x) { total += x; })

        // print each number 
        .each!writeln;
}