Write a Cout Statement That Displays the Sum of the Variables X, Y, and Z.

BASICs of C/C++ Programming

Writing simple C++ programs

Example 1

//  Simple printing code.  #include <iostream> using namespace std;  int main() { 	int a = 10, b = 20; 	     cout << "sum is" << a + b << endl; 	cout << "product is " << a*b << endl;  	return 0; }          

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A typical c++ program uses several header files in order 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 example use output operator "<<" defined in the standard name space. In this example, a user has declared two integers a and b; and, they are initialized to 10 and 20 respectively. Finally it computes the sum and products of a and b and outputs them on the console as shown below.

Example 2

//  Simple printing code. //  #include <iostream> using namespace std;  int main() { 	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;  	return 0; }          

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This example is very similar 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

Computer stores the variables in the memory. Therefore, computer needs to know what kind of data we store so that computer reserves some memory space for the variable. A Byte [B] is the minimum amount of memory space for a computer. One Byte is eight bits and a bit is either 0 or 1. 1KB=2^8=1024 Bytes Data type is defined as a set of values together with a set of operations. C++ data types may be grouped into three categories:

Simple

Structured

Pointer

Simple Data Types:

There are three categories within the simple data type

1. Integral: integer (Whole numbers)
2. Floating-point: Real numbers
3. Enumeration type: user-defined data type
4. Important Variants integral data types are
1. int
2. bool
3. Char

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

Examples:

• -6728
• 0
• 78
• +763
• P78
1. Note that + sign is optional
2. No commas should be used within an integer (e.g. 10.825 is wrong)

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

Example.1

Following program 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 main()   { 	int a=10, b=5, c; 	    c = a*b; 	        cout << "a = " << a <<", b= "<<b<<endl;  	cout << "c = " << c << endl;  	return 0; }          

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Example.1:

Following program has int a, b, and c. user can enter a and b values and calculate c. Prints a, b, and c

            #include <iostream>  using namespace std;   int main()   { 	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 habit to have prompt before cin command so that user knows that he has to respond.

bool Data Type

bool type

• Two values: true and false
• Manipulate logical (Boolean) expressions

true and false are called logical values

bool, true, and false are reserved words

char Data Type

The smallest integral data type

Used for characters: letters, digits, and special symbols

Each character is enclosed in single quotes

• 'A', 'a', '0', '*', '+', '$', '&'

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

Example

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

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Result

Example

It is good habit to have 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;   	return 0; }        

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Example

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

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Result

Real Numbers

1. C++ uses scientific notation to represent real numbers (floating-point notation or scientific notation)
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 (1.2 GHz)
3. Real 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 main()   { 	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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Result

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; }        

Result

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

This method Improves readability of your code

Examples

enum direction {North, South, East, West};

// Here North=0, South =1, East =2, and West =3

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

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

Variables

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

Example int x1; int x2; int sum;

You can declare several variables of same type in one declaration Comma separated list

int x1, x2, sum;

Variable name must be a valid identifier

Series of characters (letters, digits, underscores)

Cannot begin with digit

Case sensitive (uppercase letters are different from lowercase letters)

Use identifiers of 31 characters or fewer

Avoid identifiers that begin with underscores and double underscores, because C++ compilers may use names like that for their own purposes internally

There are some reserved keywords for C++, avoid using them as variable names.

It is better to place a space after each comma (,) to make programs more readable. If you like you can declare each variable on a separate line. So that you 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 end 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 defined outside of all the functions, usually on top of the program. The global variables are available for use the entire program after the declaration and can be accessed by any function in the program. Following are some examples using global and local variables:

Example

#include <iostream>  using namespace std;  // Global variable declaration: int Y;   int main ()   {  	// 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:Note: If a program can have same name for local and global variables, the value of local variable inside a function will take preference.

Example

#include <iostream>  using namespace std;   // Global variable declaration:   int Y;   int main ()   {  	// Local variable declaration and nitialization :   	int a=10, b=20,Y=30;  	      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

Arithmetic Operators:The following arithmetic operators supported by C++ language:

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

Example:

Example x = x+1; can be written as x++; //postfix form

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Write a Cout Statement That Displays the Sum of the Variables X, Y, and Z.

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

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