O loop do...while funciona da mesma forma que o loop while, com a exceção de a condição ser testada no final do loop, tal que o loop será executado pelo menos uma vez.
Sintaxe
do {// bloco de comandos} while (condição);
A condição é uma expressão booleana que é avaliada como verdadeiro ou falso, respectivamente true ou false na linguagem Arduino.
Código de Exemplo
Código de Exemplo 1
voidsetup() {Serial.begin(9600);Serial.println("====== TEST START ======");int i = 0;do {Serial.print("Inside the DO WHILE loop: i = ");Serial.println(i); i++; // increase i by 1 } while (i < 5);Serial.println("====== TEST END ========");}voidloop() {}
The result on Serial Monitor:
Newbiely | Arduino IDE 2.3.8
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File
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Arduino Uno
Newbiely.ino
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8Serial.println("Hello World!");
Output
Serial Monitor
Message (Enter to send message to 'Arduino Uno' on 'COM15')
New Line
9600 baud
====== TEST START ======
Inside the DO WHILE loop: i = 0
Inside the DO WHILE loop: i = 1
Inside the DO WHILE loop: i = 2
Inside the DO WHILE loop: i = 3
Inside the DO WHILE loop: i = 4
====== TEST END ========
Ln 11, Col 1
Arduino Uno on COM15
2
Código de Exemplo 2
int x = 0;do {delay(50); // espera os sensores estabilizarem x = readSensors(); // checa os sensores} while (x < 100);
do...while loop vs while loop
The while loop checks the condition before executing the block of code; conversely, the dowhile loop checks the condition after executing the block of code. Therefore, the dowhile loop will always be executed at least once, even if the condition is false at the beginning.
The do...while and while loop are the same, except for the case in which the condition is false at the beginning.
For example:
Code with do...while loop
voidsetup() {Serial.begin(9600);Serial.println("====== TEST START ======");int i = 10;do {Serial.print("Inside the DO WHILE loop: i = ");Serial.println(i); i++; // increase i by 1 } while (i < 5);Serial.println("====== TEST END ========");}voidloop() {}
Newbiely | Arduino IDE 2.3.8
──
☐
✕
File
Edit
Sketch
Tools
Help
Arduino Uno
Newbiely.ino
···
8Serial.println("Hello World!");
Output
Serial Monitor
Message (Enter to send message to 'Arduino Uno' on 'COM15')
New Line
9600 baud
====== TEST START ======
Inside the DO WHILE loop: i = 10
====== TEST END ========
Ln 11, Col 1
Arduino Uno on COM15
2
Code with while loop
voidsetup() {Serial.begin(9600);Serial.println("====== TEST START ======");int i = 10;while (i < 5) {Serial.print("Inside the DO WHILE loop: i = ");Serial.println(i); i++; // increase i by 1 }Serial.println("====== TEST END ========");}voidloop() {}
Newbiely | Arduino IDE 2.3.8
──
☐
✕
File
Edit
Sketch
Tools
Help
Arduino Uno
Newbiely.ino
···
8Serial.println("Hello World!");
Output
Serial Monitor
Message (Enter to send message to 'Arduino Uno' on 'COM15')
New Line
9600 baud
====== TEST START ======
====== TEST END ========
Ln 11, Col 1
Arduino Uno on COM15
2
※ Notas e Advertências:
There are three ways to escape the dowhile loop:
The condition of the do while loop becomes false.
The execution of the code reaches a break statement inside the loop.
The execution of the code reaches a goto statement inside the loop, which jumps to a label located outside of the loop.
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