3.9 KiB
| title | localeTitle |
|---|---|
| Loops | الحلقات |
الحلقات
المقدمة
الآن دعنا نناقش شيئًا يُعرف باسم الحلقة. افترض أنك تريد طباعة الأرقام الزوجية من 1 إلى 1000 على الشاشة. اتجاه واحد للقيام بذلك هو كتابة السطور التالية
`` `ج + + 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: `
ج ++ بينما (الشرط) { // القانون الذي سيتم تنفيذه في حين الشرط هو الصحيح } فعل { // سيتم التنفيذ مرة واحدة وحتى تصبح الحالة خاطئة } في حين (شرط) ؛
`### 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.
They are declared this way: `
ج ++ لـ (تهيئة متغير ؛ تحقق من شرط ؛ زيادة المتغير الذي تم تهيئته) { // رمز التنفيذ }
Lets write a program which will print numbers from 0 to 1000 including 1000 on the screen using a for loop.
ج ++ لـ (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.
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 ``
ج ++ لـ (int i = 0؛ i = 1000 = i = i + 2) { cout << i << endl؛ }
`` `
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الفرق في البرنامج الأول والثاني هو جزء الزيادة. بقية الكود هو نفسه. هذا البرنامج سوف يطبع 0 و ثم إضافة 2 إليه وطباعة 2 على وحدة التحكم وهكذا تصبح قيمة up تساوي 1000.
برنامجنا النهائي لطباعة حتى الأرقام من 0 إلى 1000 سيبدو هكذا.
`` `ج + +
تتضمن
استخدام اسم للمحطة؛ انت مين() { لـ (int i = 0؛ i = 1000 = i = i + 2) { cout << i << endl؛ } العودة 0 } `` `