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title	localeTitle
Loops	rotações

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Introdução

Agora vamos discutir algo conhecido como loop. Suponha que você queira imprimir os números pares de 1 a 1000 na tela. Mão única fazer isso é escrever as seguintes linhas

`` `c ++ cout << 0 << endl; cout << 2 << endl; cout << 4 << endl; … … … cout << 1000 << endl;

But the problem with this approach is that you have to write the same line again and again. And if suppose you have to print 
 prime numbers from 1 to 1000 then this will be more hectic. 
 Therefore, in order to solve such problems loops are introduced. 
 
 There are different types of loop functions: 
 ### While and do while loops 
 
 While and do while loops allow you to make the loop until a condition finishes. 
 The difference between While and Do while is that Do while always executes once. 
 Here you can see an example:

c ++ while (condição) { // Código que será executado enquanto a condição for verdadeira } Faz { // Será executado uma vez e até que a condição seja falsa } while (condição);

### For loops 
 
 For loops are usually used when you know how many times the code will execute. 
 The flow can be seen in this [graph](https://www.tutorialspoint.com/cplusplus/images/cpp_for_loop.jpg). 
 
 They are declared this way:

c ++ para (inicializar uma variável; verificar uma condição; incrementar a variável inicializada) { // Código para executar }

Lets write a program which will print numbers from 0 to 1000 including 1000 on the screen using a for loop.

c ++ para (int i = 0; i <= 1000; i ++) { cout << i << endl; }

When you execute this code in a c++ program numbers from 1 to 1000 will be printed. 
 Now lets discuss how the for loop works. 
 
 * You start a for loop by typing the keyword 'for'. It means you are starting a for loop 
 ` for ` 
 * Next you open and close a round bracket. In this brackets you write some conditions which will be discussed later 
 ` for()` 
 * Inside the brackets first you write the initial condition ie the value from where the loop will start. Like in the 
  above program we write int i = 0 
 ` for(int i = 0)` 
 * Then you write the semicolon and then condition until when the loop will be executed. In the above code you define 
   i < 1000. It means until value of i is less then 1000 execuete the loop. 
   ` for(int i=0;i<=1000) ` 
 * Then you define the incremented value that is how much i has to be incremented in each iteration. In the above code 
   we write i++. It means value of i will be incremented by 1 every time. 
    ` for(int i=0;i<=1000;i++) ` 
 * If there is only one statement inside the loop then the curly bracket is optional but its better to write loop code 
   within brackets so that you don't get confused. 
    ``` c++ 
    for(int i=0;i<=1000;i++) 
        { 
        } 
     ``` 
 * Then inside the loop you write what do you want to do. In the above program we output the value of i. 
 
 So, in this way the for loop works 
 
 If you want to print even numbers from 1 to 1000 then your program will look like this

c ++ para (int i = 0; i <= 1000; i = i + 2) { cout << i << endl; }

`` `

A diferença no primeiro programa e no segundo é a parte de incremento. O resto do código é o mesmo. Este programa imprimirá 0 e em seguida, adicione 2 a ele e imprima 2 no console e assim por diante até o valor de i se torna igual a 1000.

Nosso programa final para imprimir números pares de 0 a 1000 será assim.

`` `c ++

incluir

usando namespace std; int main () { para (int i = 0; i <= 1000; i = i + 2) { cout << i << endl; } return 0; } `` `

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