Mmm, strange

Question sur la mission

Résolues

I don't understand why the last statement doesn't work. I'm missing something..

Utilise le clavier pour saisir trois entiers. Détermine s'il existe au moins une paire de nombres égaux parmi eux.
Si une telle paire existe, affiche ces nombres séparés par un espace.
Si les trois nombres sont égaux, affiche-les tous les trois.

Voici quelques exemples :
a) Si tu saisis les nombres
1
2
2
nous affichons
2 2

b) Si tu saisis les nombres
2
2
2
nous affichons
2 2 2

Impératifs :

Le programme doit lire les nombres au clavier.
Le programme doit contenir System.out.println() ou System.out.print().
Si deux nombres sont égaux entre eux, tu dois les afficher à l'écran.
Si les trois nombres sont égaux, affiche-les tous les trois.
S'il n'y a pas de nombres égaux, n'affiche rien.

package fr.codegym.task.task04.task0417; /* Avons-nous une paire ? */ import java.io.*; import java.util.Scanner; public class Solution { public static void main(String[] args) throws Exception { //écris ton code ici Scanner sc = new Scanner(System.in); int a = sc.nextInt(); int b = sc.nextInt(); int c = sc.nextInt(); if(a == b) System.out.print(a +" "+ b + " "); else if(a == c) System.out.print(a +" "+ c + " "); else if(b == c) System.out.print(b +" "+ c + " "); else if(a == b && c == b) System.out.print(a +" "+ b +" "+ c); } }

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BenOitB

niveau Lyon, Lyon, France

7 juin 2021, 06:19

Hi Guadalupe, thx again for all your explanations ;). I Put your post-link in my fav' ^^. I started the first video, very instructive !

BenOitB

niveau Lyon, Lyon, France

4 juin 2021, 07:02

Mmm, What i understand, after a good night and after re-reading your reply, is that this first statment is not disregarded anymore because i wrote it at the first place (and the program will read it no mater what). As it's not true in that case, it will pass to the other one until the compiler find a true statment and execute it. Am i right ? or i miss it again xD ?

Guadalupe Gagnon

niveau Tampa, Tampa, United States

4 juin 2021, 14:14

utile

Yes. So, in abstract terms, here is how if-else if statements work:

if(/*expression1*/){
   // code block 1
} else if(/*expression2*/){
   // code block 2
}  else {
   // code block 3
}
// line 8

Java is going to start at the very top and check the first expression. If it is true then the code in code block 1 will execute and then it goes to the very bottom of the structure (line 8 in this code) and continues from there. If the expressions is false then it skips to expression2. If that is true then code in code block 2 gets executed and then it moves to line 8. It does this behavior for as many expressions as you have that are part of the structure. If none of the expressions are true then it will reach the single 'else' block, which you can think of as a default code to run if nothing else is true. When you use "if-else if" you must ensure that it is set up logically so that you don't execute a block of code that captures something early. For example, in your code you had the expression checking where all three numbers are the same at the bottom of the structure, but because the first if statement of the structure started by checking if two 2 numbers were the same it captured the case where all 3 numbers were the same. It executed code block one then moved right to the end of the structure and continued from there. Most people think that computer programming is about creating complex algorithms using advanced techniques that you need to be nearly a genius to understand. This is not true. In actuality you need to learn how to explain things, step by step, in a way that even the dumbest person on earth could understand. Computers have no ability to think and only do EXACTLY what you tell them to do. Check out my forum post that shares some videos I found useful. They are in English though:

BenOitB

niveau Lyon, Lyon, France

3 juin 2021, 16:10

Hi Guadalpe. Thank you. Apprently i had to write if(a == b && c == b) System.out.print(a +" "+ b +" "+ c); at the very beginning. But i still don't understand.

Guadalupe Gagnon

niveau Tampa, Tampa, United States

3 juin 2021, 17:07

What are your thoughts on the reason why?

Guadalupe Gagnon

niveau Tampa, Tampa, United States

2 juin 2021, 16:42

"if-else if" statements will only execute the first block of code where the if statement is true; all other if statements are disregarded. In this code, when a, b, and c are all the same, then line 18 will be true and that block of code will be executed.