Mastering Conditional Iteration with Go's for Loop

Welcome back! I hope you're prepared for another exciting lesson. Our journey through loops in Go continues. You've already built a strong foundation. Now, we'll enrich that knowledge by exploring how to use a conditional for loop in Go.

Think of a for loop with a condition in Go as your reliable companion that continues performing a task as long as the condition remains true. It keeps iterating until the condition fails or a break statement intervenes. Let's illustrate how this works with a code snippet related to planning a trip based on the budget for the countries you want to visit:

package main

import (
    "fmt"
)

func main() {
    // We have a budget for the trip, and each country costs a certain amount
    travelBudget := 5000
    countryCosts := map[string]int{"France": 1000, "Italy": 800, "Spain": 900, "Japan": 1200}

    totalCost := 0
    chosenCountries := []string{}

    // Let's add countries to our trip until our budget runs out using a for loop
    for totalCost < travelBudget && len(countryCosts) > 0 {
        // Iterate over map to get a country and its cost
        tried := 0
        for country, cost := range countryCosts {
            if totalCost+cost <= travelBudget {
                totalCost += cost
                chosenCountries = append(chosenCountries, country)
                delete(countryCosts, country)
            } else {
                tried++
            }
        }
        
        if len(countryCosts) == tried {
            // we don't have any more options that can fit within our budget so we can safely exist the loop
            break;
        }
    }

    fmt.Println("Countries chosen for the trip:", chosenCountries)
}

This code features a for loop that checks two conditions — whether our totalCost is less than our travelBudget, and whether there are still countries left in the countryCosts map. The loop continues iterating, removing countries from the map, and adding them to our trip until one of the conditions fails.

We are also monitoring how many countries we have checked within our loop. If it so happens that the count of countries checked matches the length of the collection of contries, we have exhausted our options and can exit our loop.

In this case, our budget permits travel to all the countries, so the loop stops when countryCosts is empty and there are no more countries to consider. If you adjust the travelBudget to a lower number, the loop will halt sooner when the first condition is no longer met.