# C++ Programming Code Examples

## C++ > Mathematics Code Examples

### Check Whether a Number can be Express as Sum of Two Prime Numbers.

/* Check Whether a Number can be Express as Sum of Two Prime Numbers. */ #include <iostream> using namespace std; int main() { int n, i, flg1 = 1, flg2 = 1, flg3 = 0, j; float sum = 0; cout << "\n\n Check Whether a Number can be Express as Sum of Two Prime Numbers:\n"; cout << "------------------------------------------------------------------------\n"; cout << " Input a positive integer: "; cin >> n; for (i = 3; i <= n / 2; i++) { /*---------- check for prime---------------*/ flg1 = 1; flg2 = 1; for (j = 2; j < i; j++) { if (i % j == 0) { flg1 = 0; j = i; } } for (j = 2; j < n - i; j++) { if ((n - i) % j == 0) { flg2 = 0; j = n - i; } } if (flg1 == 1 && flg2 == 1) { cout << n << " = " << i << " + " << n - i << endl; flg3 = 1; } } if (flg3 == 0) { cout << n << " can not be expressed as sum of two prime numbers." << endl; } }

Logical Operators are used to compare and connect two or more expressions or variables, such that the value of the expression is completely dependent on the original expression or value or variable. We use logical operators to check whether an expression is true or false. If the expression is true, it returns 1 whereas if the expression is false, it returns 0. Assume variable A holds 1 and variable B holds 0:

In computer programming, we use the if statement to run a block code only when a certain condition is met. An if statement can be followed by an optional else statement, which executes when the boolean expression is false. There are three forms of if...else statements in C++: • if statement, • if...else statement, • if...else if...else statement, The if statement evaluates the condition inside the parentheses ( ). If the condition evaluates to true, the code inside the body of if is executed. If the condition evaluates to false, the code inside the body of if is skipped.

Consider a situation, when we have two persons with the same name, jhon, in the same class. Whenever we need to differentiate them definitely we would have to use some additional information along with their name, like either the area, if they live in different area or their mother's or father's name, etc. Same situation can arise in your C++ applications. For example, you might be writing some code that has a function called xyz() and there is another library available which is also having same function xyz(). Now the compiler has no way of knowing which version of xyz() function you are referring to within your code.

Arithmetic Operator is used to performing mathematical operations such as addition, subtraction, multiplication, division, modulus, etc., on the given operands. For example: 6 + 3 = 9, 5 - 3 = 2, 3 * 4 = 12, etc. are the examples of arithmetic operators. Let's discuss the different types of Arithmetic Operators in the C programming. Plus Operator is a simple Plus (+) Operator used to add two given operands. We can use Plus Operator with different data types such as integer, float, long, double, enumerated and string type data to add the given operand. The minus operator is denoted by the minus (-) symbol. It is used to return the subtraction of the first number from the second number. The data type of the given number can be different types, such as int, float, double, long double, etc., in the programing language.

A program shall contain a global function named main, which is the designated start of the program in hosted environment. main() function is the entry point of any C++ program. It is the point at which execution of program is started. When a C++ program is executed, the execution control goes directly to the main() function. Every C++ program have a main() function.

C supports nesting of loops in C. Nesting of loops is the feature in C that allows the looping of statements inside another loop. Any number of loops can be defined inside another loop, i.e., there is no restriction for defining any number of loops. The nesting level can be defined at n times. You can define any type of loop inside another loop; for example, you can define 'while' loop inside a 'for' loop. A loop inside another loop is called a nested loop. The depth of nested loop depends on the complexity of a problem. We can have any number of nested loops as required. Consider a nested loop where the outer loop runs n times and consists of another loop inside it. The inner loop runs m times. Then, the total number of times the inner loop runs during the program execution is n*m.

In computer programming, loops are used to repeat a block of code. For example, when you are displaying number from 1 to 100 you may want set the value of a variable to 1 and display it 100 times, increasing its value by 1 on each loop iteration. 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. A for loop is a repetition control structure that allows you to efficiently write a loop that needs to execute a specific number of times.

The cin object is used to accept input from the standard input device i.e. keyboard. It is defined in the iostream header file. C++ cin statement is the instance of the class istream and is used to read input from the standard input device which is usually a keyboard. The extraction operator(>>) is used along with the object cin for reading inputs. The extraction operator extracts the data from the object cin which is entered using the keyboard. The "c" in cin refers to "character" and "in" means "input". Hence cin means "character input". The cin object is used along with the extraction operator >> in order to receive a stream of characters.

#include is a way of including a standard or user-defined file in the program and is mostly written at the beginning of any C/C++ program. This directive is read by the preprocessor and orders it to insert the content of a user-defined or system header file into the following program. These files are mainly imported from an outside source into the current program. The process of importing such files that might be system-defined or user-defined is known as File Inclusion. This type of preprocessor directive tells the compiler to include a file in the source code program.

This program sorts the 10 strings (entered by the user) in Lexicographical order (dictionary order). This program takes 10 words from the user and sort them in 'Lexicographical Order'

To swap two numbers in C++, ask to the user to enter the two number, and store both the number in the variable say num1 and num2. Now to swap both the number, first, make a

A simple c++ program which shows using of switch statement in c++. C++ Program which takes input a grade and display Grade Points Average GPA. Program takes inputs A,a, B,b,

In C++ programming, "signals" are interrupts of software which is delivered to a process by the OS ("operating system"). Signals can also be issued by the OS on the basis of system or