Challenge 1 - Concurrency

Write a program combining goroutines, channels and WaitGroup.

Challenge: a parallel word counter

You will write a program that processes several texts at once and finds the total word count. Each text is counted in its own goroutine, the results are collected on a channel, and the end of all goroutines is awaited with a sync.WaitGroup.

metinler := []string{
    "go hızlı ve basit",
    "kanallar goroutine'leri bağlar",
    "eşzamanlılık paralellik değildir",
}
// expected total: 10

Use strings.Fields to count words; it handles multiple spaces and newlines correctly.

Plan

1) sonuc := make(chan int, len(metinler)) — a buffer with room for every goroutine. 2) For each text, wg.Add(1) + a goroutine: sonuc <- len(strings.Fields(m)). 3) wg.Wait(), then close(sonuc). 4) Sum with for n := range sonuc. Thanks to the buffer, Wait and close can safely happen in the same goroutine.

Exercise Write the counter

Write the program following the plan and print the total word count.

Show example solution

package main

import (
    "fmt"
    "strings"
    "sync"
)

func main() {
    metinler := []string{
        "go hızlı ve basit",
        "kanallar goroutine'leri bağlar",
        "eşzamanlılık paralellik değildir",
    }
    sonuc := make(chan int, len(metinler))
    var wg sync.WaitGroup
    for _, m := range metinler {
        wg.Add(1)
        go func(m string) {
            defer wg.Done()
            sonuc <- len(strings.Fields(m))
        }(m)
    }
    wg.Wait()
    close(sonuc)
    toplam := 0
    for n := range sonuc {
        toplam += n
    }
    fmt.Println(toplam)
}

Test yourself

How many elements does <code>strings.Fields(" a b ")</code> return?
- 2
- 5
- 3
- 7
Show answer

2 — Fields treats consecutive spaces as one separator and drops leading/trailing spaces; Split(" ") would produce empty pieces.

Split the words

n := len(strings.____(metin))

Show answer

n := len(strings.Fields(metin))

Piece and role

goroutine

Counts one text
The sonuc channel

Carries the counts
wg.Wait

Waits for all to finish
range sonuc

Sums

Next lesson: Challenge 2 - HTTP service

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