86 lines
3.9 KiB
Markdown
86 lines
3.9 KiB
Markdown
---
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title: Loops
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localeTitle: الحلقات
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---
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# الحلقات
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## المقدمة
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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
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\`\` \`ج + + cout << 0 << endl؛ cout << 2 << endl؛ cout << 4 << endl؛ .... .... .... cout << 1000 << endl؛
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```
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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
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prime numbers from 1 to 1000 then this will be more hectic.
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Therefore, in order to solve such problems loops are introduced.
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There are different types of loop functions:
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### While and do while loops
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While and do while loops allow you to make the loop until a condition finishes.
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The difference between While and Do while is that Do while always executes once.
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Here you can see an example:
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```
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ج ++ بينما (الشرط) { // القانون الذي سيتم تنفيذه في حين الشرط هو الصحيح } فعل { // سيتم التنفيذ مرة واحدة وحتى تصبح الحالة خاطئة } في حين (شرط) ؛
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```
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### For loops
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For loops are usually used when you know how many times the code will execute.
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The flow can be seen in this [graph](https://www.tutorialspoint.com/cplusplus/images/cpp_for_loop.jpg).
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They are declared this way:
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```
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ج ++ لـ (تهيئة متغير ؛ تحقق من شرط ؛ زيادة المتغير الذي تم تهيئته) { // رمز التنفيذ }
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```
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Lets write a program which will print numbers from 0 to 1000 including 1000 on the screen using a for loop.
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```
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ج ++ لـ (int i = 0؛ i <= 1000؛ i ++) { cout << i << endl؛ }
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``When you execute this code in a c++ program numbers from 1 to 1000 will be printed.
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Now lets discuss how the for loop works.
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* You start a for loop by typing the keyword 'for'. It means you are starting a for loop
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` for `
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* Next you open and close a round bracket. In this brackets you write some conditions which will be discussed later
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` for()`
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* Inside the brackets first you write the initial condition ie the value from where the loop will start. Like in the
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above program we write int i = 0
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` for(int i = 0)`
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* Then you write the semicolon and then condition until when the loop will be executed. In the above code you define
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i < 1000. It means until value of i is less then 1000 execuete the loop.
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` for(int i=0;i<=1000) `
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* Then you define the incremented value that is how much i has to be incremented in each iteration. In the above code
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we write i++. It means value of i will be incremented by 1 every time.
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` for(int i=0;i<=1000;i++) `
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* If there is only one statement inside the loop then the curly bracket is optional but its better to write loop code
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within brackets so that you don't get confused.
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```cpp
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for(int i=0;i<=1000;i++)
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{
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}
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```
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* Then inside the loop you write what do you want to do. In the above program we output the value of i.
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So, in this way the for loop works
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If you want to print even numbers from 1 to 1000 then your program will look like this
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```cpp
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لـ (int i = 0؛ i = 1000 = i = i + 2) { cout << i << endl؛ }
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```
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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.
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برنامجنا النهائي لطباعة حتى الأرقام من 0 إلى 1000 سيبدو هكذا.
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\`\` \`ج + +
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# تتضمن
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استخدام اسم للمحطة؛ انت مين() { لـ (int i = 0؛ i = 1000 = i = i + 2) { cout << i << endl؛ } العودة 0 } \`\` \` |