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About Functions in c++
Branch: Mechatronics نكسكاترومي :الفرع
study: morning صباحي :الدراسة
stage: first األولى:المرحلة
date 4 / 5 /
We often use functions to a arrange the code groups to perform a
specific task.
Depending on whether a function is predefined or created by
programmer; there are two types of function:
- Library Function
- User-defined Function Library Functions: Library functions are the built-in function in C++ programming. Programmers can use library, and then call the function directly; they don't need to write it themselves. Example 1: Library Function #include <iostream.h> #include <math.h> int main() { double number, squareRoot; cout << "Enter a number: "; cin >> number; // sqrt() تعرف الجذر التربيعي مخزونة في المكتبة مسبقا دالة squareRoot = sqrt(number); cout << "Square root of " << number << " = " << squareRoot; return 0 ; }
It happens like the figure shows Consider the figure above.
When the program is in the main() function, the system starts executing codes
from main() function.
When the program reaches to function_name() inside main(), it moves to void
function_name() and all codes inside void function_name() is executed.
Then, control of the program moves back to the main function where the code after the call to the function_name() is executed as shown in figure above. Example 2: User Defined Function C++ program to add two integers. Make a function add() to add integers and display sum in main() function. #include <iostream.h> using namespace std; // تعريف عناصر الدالة int add(int, int);
int main() { int num1, num2, sum; cout<<"Enters two numbers to add: "; cin >> num1 >> num2; // استدعاء الدالة sum = add(num1, num2); cout << "Sum = " << sum; return 0 ; } // تعريف الدالة int add(int a, int b) { int add; add = a + b; // االرجاع return add; } Output Enters two integers: 8
In the above program, add(num1,num2); inside main() function calls the
user-defined function.
The function returns an integer which is stored in variable add.
Function Definition
The function itself is referred as function definition. Function
definition in the above program is:
// Function definition
int add (int a, int b);
int add;
add = a + b;
return add;
When the function is called, control is transferred to the first
statement of the function body.
Then, other statements in function body are executed sequentially.
When all codes inside function definition is executed, control of
program moves to the calling program.
المصادر: www.programiz.com, "++ ي " موسوعة البر مجة بلغة سc++ book
