Design and Implement an Application That Reads an Integer Value and Prints the Sum of All Even

BASICs of C/C++ Programming

Writing simple C++ programs

Instance ane

//  Simple printing lawmaking.  #include <iostream> using namespace std;  int main() { 	int a = x, b = 20; 	     cout << "sum is" << a + b << endl; 	cout << "product is " << a*b << endl;  	render 0; }          

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A typical c++ program uses several header files in gild to use the library routines that has been developed already. In the above example, the statement #include <iostream> indicates that we need the I/O library. The statement "#using namespace std;" says that this instance use output operator "<<" divers in the standard proper name space. In this example, a user has declared two integers a and b; and, they are initialized to ten and 20 respectively. Finally it computes the sum and products of a and b and outputs them on the console every bit shown below.

Example 2

//  Simple printing lawmaking. //  #include <iostream> using namespace std;  int primary() { 	int a, b; 	cout << "Input a:"; cin >> a; 	     cout << "Input b:"; cin >> b; 	     cout << "sum is" << a + b << endl; 	     cout << "product is " << a*b << endl;  	render 0; }          

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This example is very like to the previous one except that the user inputs the values "a" and "b" and they are read using the input operator "cin". Finally the code calculates and prints the values of the sum and product of a and b

Data types

Figurer stores the variables in the memory. Therefore, computer needs to know what kind of data nosotros store so that computer reserves some retention infinite for the variable. A Byte [B] is the minimum amount of retentivity space for a computer. 1 Byte is eight $.25 and a chip is either 0 or 1. 1KB=2^8=1024 Bytes Information type is defined as a set of values together with a prepare of operations. C++ information types may be grouped into three categories:

Unproblematic

Structured

Arrow

Simple Information Types:

There are 3 categories within the simple data type

1. Integral: integer (Whole numbers)
2. Floating-indicate: Existent numbers
3. Enumeration type: user-divers information blazon
4. Important Variants integral information types are
1. int
2. bool
3. Char

It is also the number of bytes taken by a data blazon is compiler dependent. brusk or short int information type covers whole numbers that can exist positive or negative (-128 to 127). unsigned short int takes but positive number (0 to 255)

Examples:

• -6728
• 0
• 78
• +763
• P78
1. Annotation that + sign is optional
2. No commas should be used inside an integer (e.grand. 10.825 is incorrect)

In order to apply a variable in C++, the variables should be alleged first with the types.

Instance.ane

Post-obit programme has int a, b, and c. a and b values are given and find c. Prints a, b, and c

#include <iostream>  using namespace std;   int principal()   { 	int a=ten, b=5, c; 	    c = a*b; 	        cout << "a = " << a <<", b= "<<b<<endl;  	cout << "c = " << c << endl;  	return 0; }          

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Example.ane:

Post-obit program has int a, b, and c. user tin can enter a and b values and summate c. Prints a, b, and c

            #include <iostream>  using namespace std;   int principal()   { 	int a, b, c;  	cout<<"Enter integer a and b values :";  	cin>>a>>b; 	c = a*b;  	cout << "a = " << a <<", b= "<<b<<endl;  	cout << "c = " << c << endl;  	return 0; }          

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It is good addiction to have prompt before cin command then that user knows that he has to answer.

bool Data Type

bool blazon

• Two values: truthful and imitation
• Manipulate logical (Boolean) expressions

true and false are called logical values

bool, truthful, and false are reserved words

char Data Blazon

The smallest integral information blazon

Used for characters: letters, digits, and special symbols

Each graphic symbol is enclosed in single quotes

• 'A', 'a', '0', '*', '+', '$', '&'

A blank space is a grapheme and is written ' ', with a infinite left between the single quotes

Example

#include <iostream>  using namespace std;   int main()   { 	char x1='C';  	char x2='P';  	cout<<" This is a examination..."<<endl;  	cout<<"Answer : "<<x1<<x2<<x2<<endl;  	render 0; }        

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Result

Example

It is good habit to accept prompt before cin command so that user knows that he has to respond.

#include <iostream>  using namespace std;   int main()   { 	char x1='C', x2='P';  	cout<<" This is a test..."<<endl;  	cout<<" Answer : "<<x1<<x2<<x2<<endl;  	cout<<endl;   	render 0; }        

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Instance

#include <iostream>  using namespace std;   int main()   { 	char x1, x2;  	cout<<" Enter x1 and x2 chacaters:";  	cin>>x1>>x2;  	cout<<" This is a examination..."<<endl;  	cout<<" Answer : "<<x1<<x2<<x2<<endl;  	cout<<endl;    return 0;  }        

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Result

Real Numbers

1. C++ uses scientific annotation to represent real numbers (floating-point annotation or scientific note)
2. This allows a user to represent too small and too large numbers
1. 3.141592
2. 0.3679
3. 1.602e-19
4. 3.4e+64 ( 50! Fifty factorial)
5. 1.2e9 (1.ii GHz)
3. Existent numbers may be classified as float and double

[We always use double in our code as it is more accurate than float]

Example

#include <iostream>  using namespace std;   int primary()   { 	double x1, x2;  	cout<<" Enter x1 and x2 double numbers:";  	cin>>x1>>x2;  	cout<<" This is a test..."<<endl;  	cout<<" Total : "<< x1 <<" + "<< x2 <<" = "<< x1+x2 << endl;  	cout<<endl;    return 0; }        

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Consequence

Example

#include <iostream>  using namespace std;   int main()   { 	double x1, x2, full;  	cout<<" Enter x1 and x2 double numbers:";  	cin>>x1>>x2; 	total=x1+x2;  	cout<<endl;  	cout<<" Total : "<< x1 <<" + "<< x2 <<" = "<< total << endl;  	cout<<endl;    return 0; }        

Result

Enumerated data types allows to designate a symbolic name for each integer.

This method Improves readability of your code

Examples

enum direction {Due north, South, East, West};

// Here North=0, S =1, Eastward =2, and Due west =iii

enum radixchoice {binary, octal, decimal, hex};

Now one define a variable around this enumerated type management myheading = East; radixchoice mybase=hex;

Variables

Variable is a location in memory where a value can exist stored. Declare variables with data blazon and name before use

Example int x1; int x2; int sum;

You lot can declare several variables of same blazon in one annunciation Comma separated list

int x1, x2, sum;

Variable name must exist a valid identifier

Series of characters (messages, digits, underscores)

Cannot begin with digit

Case sensitive (uppercase letters are different from lowercase messages)

Employ identifiers of 31 characters or fewer

Avert identifiers that brainstorm with underscores and double underscores, because C++ compilers may utilise names like that for their ain purposes internally

In that location are some reserved keywords for C++, avoid using them as variable names.

It is meliorate to place a infinite later each comma (,) to brand programs more readable. If yous like yous tin declare each variable on a carve up line. And then that yous to place a comment next to each declaration

It is better to place declarations at the beginning of a function and separate them from the executable statements with one blank line to highlight where the declarations cease and the executable statements begin

The following list shows the some reserved words in C++. These reserved words may not be used as constant or variable or any other identifier names.

Example

          #include <iostream>  using namespace std;   int main()   { 	double x1, x2, total;  	cout<<" Enter x1 and x2 double numbers:";  	cin>>x1>>x2; 	total=x1+x2;  	cout<<endl;  	cout<<" Total : "<< x1 <<" + "<< x2 <<" = "<< total << endl;  	cout<<endl;    return 0; }        

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Global Variables:

Global variables are divers outside of all the functions, usually on meridian of the program. The global variables are bachelor for utilise the entire program after the annunciation and can exist accessed by any role in the program. Following are some examples using global and local variables:

Example

#include <iostream>  using namespace std;  // Global variable declaration: int Y;   int principal ()   {  	// Local variable declaration:   	int a, b; // actual initialization   	a =10;   	b =20;   	Y = a + b;   	cout <<"The total is :"<< Y<<endl;     return 0; }        

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Result

Note:Notation: If a program can take same name for local and global variables, the value of local variable inside a function volition accept preference.

Example

#include <iostream>  using namespace std;   // Global variable declaration:   int Y;   int primary ()   {  	// Local variable declaration and nitialization :   	int a=x, b=xx,Y=xxx;  	      Y = a + b + Y;   	cout <<"The total is :"<< Y << endl;    return 0; }        

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Result

Operators:

Operators tells the compiler to perform specific mathematical or logical operations. C++ has following built-in operators:

Arithmetic Operators

Relational Operators

Logical Operators

Bitwise Operators

Assignment Operators

Arithmetics Operators:The following arithmetic operators supported past C++ linguistic communication:

The increase operator ++ adds 1 to its operand, and the decrement operator -- subtracts ane from its operand

Example:

Example x = ten+ane; can be written equally ten++; //postfix grade

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Source: https://www.cpp.edu/~elab/ECE114/Basic-of-C++.html

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