C++ Functions C++ Conditions.pptx vd.pptx

http://www.mahergelle.com
By Eng.Adulahi M. Adan
C++

Chapter Three: -
Loops, Arrays and
Functions

C++ Loops
 Often when you write code, you want the same block of
code to run over and over again in a row. Instead of adding
several almost equal code-lines in a script, we can use
loops to perform a task like this.
 In C++, we have the following looping statements:
 while - loops through a block of code as long as the
specified condition is true
 do...while - loops through a block of code once, and then
repeats the loop as long as the specified condition is true
 for - loops through a block of code a specified number of
times
Contents

C++ Loops
 The C++ while Loop
 The while loop executes a block of code as long as the
specified condition is true.
 Syntax
 while (condition) {
// code block to be executed
}
 Example
Contents
int i = 0;
while (i < 5) {
cout << i << "n";
i++; }

C++ Loops
 The C++ do...while Loop
 The do/while loop is a variant of the while loop. This loop
will execute the code block once, before checking if the
condition is true, then it will repeat the loop as long as the
condition is true.
 Syntax Example
 do {
}
while (condition);
Contents
int i = 0;
do {
cout << i << "n";
i++;
}
while (i < 5);

C++ Loops
 The C++ for Loop
 When you know exactly how many times you want to loop through
a block of code, use the for loop instead of a while loop:
 Syntax
 for (statement 1; statement 2; statement 3) {
}
 Example
Contents
for (int i = 0; i < 5; i++) {
cout << i << "n";
}

C++ Arrays
 Arrays are used to store multiple values in a single
variable, instead of declaring separate variables for each
value.
 To declare an array, define the variable type, specify the
name of the array followed by square brackets and
specify the number of elements it should store
 string cars[4];
 We have now declared a variable that holds an array of
four strings. To insert values to it, we can use an array
literal - place the values in a comma-separated list, inside
curly braces:
 string cars[4] = {"Volvo", "BMW", "Ford", "Mazda"};
Contents

#include <iostream>
#include <string>
using namespace std;
int main() {
string cars[4] = {"Volvo",
"BMW", "Ford", "Mazda"};
cout << cars[0];
return 0;
}
C++ Arrays
 Access the Elements of an Array
 You access an array element by referring to the index
number inside square brackets [].
 This statement accesses the value of the first
element in cars:
 Example
Contents

C++ Functions
 A function is a block of code which only runs when it is
called.
 You can pass data, known as parameters, into a function.
 Functions are used to perform certain actions, and they are
important for reusing code: Define the code once, and use
it many times.
Contents

C++ Functions
 Create a Function
 C++ provides some pre-defined functions, such as main(),
which is used to execute code. But you can also create
your own functions to perform certain actions.
 To create (often referred to as declare) a function, specify
the name of the function, followed by parentheses ():
 Syntax
 void myFunction() {
// code to be executed
}
Contents

C++ Functions
 Call a Function
 Declared functions are not executed immediately. They are
"saved for later use", and will be executed later, when they are
called.
 To call a function, write the function's name followed by two
parentheses () and a semicolon ;
 In the following example, myFunction() is used to print a text
(the action), when it is called
 Function Declaration and Definition
 A C++ function consist of two parts:
 void myFunction() { // declaration
// the body of the function (definition)
}
Contents

C++ Functions
 Example
Contents
#include <iostream>
void myFunction() {
cout << "I just got executed!";
}
int main() {
myFunction();
return 0;
}

C++ Function Parameters
 Information can be passed to functions as a parameter.
Parameters act as variables inside the function.
 Parameters are specified after the function name, inside
the parentheses. You can add as many parameters as you
want, just separate them with a comma
 Syntax
 void functionName(parameter1, parameter2, parameter3) {
// code to be executed
}
Contents

C++ Function Parameters
 Example
Contents
#include <iostream>
void myFunction(string fname) {
cout << fname << " Refsnesn";
}
int main() {
myFunction("Liam");
myFunction("Jenny");
myFunction("Anja");
return 0; }

C++ Default Parameters
 Default Parameter Value
 You can also use a default parameter value, by
using the equals sign (=).
 If we call the function without an argument, it
uses the default value ("Norway"):
Contents

C++ Default Parameters
 Example
Contents
#include <iostream>
void myFunction(string country = "Norway") {
cout << country << "n";
}
int main() {
myFunction("Sweden");
myFunction("India");
myFunction();
myFunction("USA");
return 0; }

Multiple Parameters
 Multiple Parameters
 Inside the function, you can add as many
parameters as you want:
Contents

Multiple Parameters
 Example
#include <iostream>
void myFunction(string fname, int age) {
cout << fname << " Refsnes. " << age << " years old. n";
}
int main() {
myFunction("Liam", 3);
myFunction("Jenny", 14);
myFunction("Anja", 30);
return 0;
}
Contents

Return Values
 The void keyword, used in the previous examples, indicates
that the function should not return a value.
 If you want the function to return a value, you can use a data
type (such as int, string, etc.) instead of void, and use the
return keyword inside the function. Example
Contents
#include <iostream>
int myFunction(int x) {
return 5 + x;
}
int main() {
cout << myFunction(3);
return (0);
}

Return Values
This example returns the sum of a function with two parameters:
Contents
#include <iostream>
int myFunction(int x, int y) {
return x + y;
}
int main() {
cout << myFunction(5, 3);
return 0;
}

Return Values
You can also store the result in a variable:
Contents
#include <iostream>
int myFunction(int x, int y) {
return x + y;
}
int main() {
int z = myFunction(5, 3);
cout << z;
return 0;
}

Final Exam
PHP AND C++
Part One: - Multiple Choose (15 * 1 = 15 M) 2page
Part Two : - Define (5 *2 = 10 M) 1 page
Part Three: - Code (5 * 3 = 15 M)
Part Four: - True or False (10 M) 1page
COMPUTER HARDWARE AND DATABASE 1
Part One: - Multiple Choose (10 * 2 = 20 M)
Part Two: - True or False (10*1=10 M)
Part Three: - Match(10*1=10 M)
Part Four: - Define (5*2= 10 M)

Thank you
@Eng.Abdulahi Mohamed

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