 # C++ Programming Code Examples

## C++ > Mathematics Code Examples

### C++ Program to Check Armstrong Number

/* C++ Program to Check Armstrong Number Example to check whether an integer (entered by the user) is an Armstrong number or not using while loop and if...else statement. A positive integer is called an Armstrong number if the sum of cubes of individual digit is equal to that number itself. For example: 153 = 1 * 1 * 1 + 5 * 5 * 5 + 3 * 3 * 3 // 153 is an Armstrong number. 12 is not equal to 1 * 1 * 1 + 2 * 2 * 2 // 12 is not an Armstrong number. In the above program, a positive integer is asked to enter by the user which is stored in the variable origNum. Then, the number is copied to another variable num. This is done because we need to check the origNum at the end. Inside the while loop, last digit is separated from num by the operation digit = num % 10;. This digit is cubed and added to the variable sum. Now, the last digit is discarded using the statement num /= 10;. In the next cycle of while loop, second last digit is separated, cubed and added to sum. This continues until no digits are left in num. Now, the total sum sum is compared to the original number origNum. If the numbers are equal, the entered number is an Armstrong number. If not, the number isn't an Armstrong number. */ #include <iostream> using namespace std; int main() { int origNum, num, rem, sum = 0; cout << "Enter a positive integer: "; cin >> origNum; num = origNum; while(num != 0) { digit = num % 10; sum += digit * digit * digit; num /= 10; } if(sum == origNum) cout << origNum << " is an Armstrong number."; else cout << origNum << " is not an Armstrong number."; return 0; }

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.

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.

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.

As the name already suggests, these operators help in assigning values to variables. These operators help us in allocating a particular value to the operands. The main simple assignment operator is '='. We have to be sure that both the left and right sides of the operator must have the same data type. We have different levels of operators. Assignment operators are used to assign the value, variable and function to another variable. Assignment operators in C are some of the C Programming Operator, which are useful to assign the values to the declared variables. Let's discuss the various types of the assignment operators such as =, +=, -=, /=, *= and %=. The following table lists the assignment operators supported by the C language:

#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.

In while loop, condition is evaluated first and if it returns true then the statements inside while loop execute, this happens repeatedly until the condition returns false. When condition returns false, the control comes out of loop and jumps to the next statement in the program after while loop. The important point to note when using while loop is that we need to use increment or decrement statement inside while loop so that the loop variable gets changed on each iteration, and at some point condition returns false. This way we can end the execution of while loop otherwise the loop would execute indefinitely. A while loop that never stops is said to be the infinite while loop, when we give the condition in such a way so that it never returns false, then the loops becomes infinite and repeats itself indefinitely.

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.

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.

The Bubble Sort is a simple sorting algorithm that 'repeatedly' steps through the List to be sorted, compares each pair of adjacent items and swaps them if they're in the wrong order.

This C++ Program checks whether a directed graph is weakly connected or not. We can do "DFS" V times starting from every vertex. If any DFS, doesn't visit all vertices, then graph