C# Program to find Composite Number

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What is Composite Number?

A positive integer that has at least one divisor other than 1 and itself.

Tips: It is recommended to use our online Composite Numbers calculator for better understanding.

Examples

The following table provides few examples of composite numbers.

NumberDivisorResult
131, 13Not a Composite Number
151, 3, 5, 15Composite Number
471, 47Not a Composite Number

Using for loop

In the following example, we will check whether the number 12 is a Composite number or not using for loop.

Example

C# Compiler
using System; namespace myApp { class Program { static void Main(string[] args) { int num = 12; int i; int count = 0; for(i=1; i<=num; i++) { if(num % i == 0) count++; } if(count > 2) Console.Write("{0} is a composite number", num); else Console.Write("{0} is not a composite number", num); } } }

Output

12 is a composite number

Using while loop

In the following example, we will check whether the number 12 is a Composite number or not using while loop.

Example

C# Compiler
using System; namespace myApp { class Program { static void Main(string[] args) { int num = 12; int i = 1; int count = 0; while(num >= i) { if(num % i == 0) count++; i++; } if(count > 2) Console.Write("{0} is a composite number", num); else Console.Write("{0} is not a composite number", num); } } }

Output

12 is a composite number

Using do while loop

In the following example, we will check whether the number 12 is a Composite number or not using do while loop.

Example

C# Compiler
using System; namespace myApp { class Program { static void Main(string[] args) { int num = 12; int i = 1; int count = 0; do{ if(num % i == 0) count++; i++; }while(i<= num); if(count > 2) Console.Write("{0} is a composite number", num); else Console.Write("{0} is not a composite number", num); } } }

Output

12 is a composite number

Composite Numbers between the Given Range

In the following example, we will find all the Composite numbers between 1 and 10.

Example

C# Compiler
using System; namespace myApp { class Program { static void Main(string[] args) { int start = 1; int end = 10; int count = 0; int i = 1; Console.WriteLine("Composite Numbers between {0} and {1}: ", start, end); for(start=start; start<=end; start++) { for(i=1; i<=start; i++) { if(start % i == 0) count++; } if(count > 2) Console.Write("{0} ", start); count = 0; } } } }

Output

Composite Numbers between 1 and 10: 4 6 8 9 10

Check Whether the Given Number is Prime or Composite

In the following example, we will check whether the given number is a Prime number or Composite number.

Example

C# Compiler
using System; namespace myApp { class Program { static void Main(string[] args) { Console.Write("Enter a (int) number: "); int num = Convert.ToInt32(Console.ReadLine()); int i; int count = 0; for(i=1; i<=num; i++) { if(num % i == 0) count++; } if(count == 2) Console.Write("{0} is a prime number", num); else Console.Write("{0} is a composite number", num); } } }

Output

Enter a (int) number: 16 16 is a composite number

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