Program to check Armstrong Number.

armstrong.cpp

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+// C++ program to determine whether the number is
+// Armstrong number or not
+#include <bits/stdc++.h>
+using namespace std;
+
+/* Function to calculate x raised to the power y */
+int power(int x, unsigned int y)
+{
+	if (y == 0)
+		return 1;
+	if (y % 2 == 0)
+		return power(x, y / 2) * power(x, y / 2);
+	return x * power(x, y / 2) * power(x, y / 2);
+}
+
+/* Function to calculate order of the number */
+int order(int x)
+{
+	int n = 0;
+	while (x) {
+		n++;
+		x = x / 10;
+	}
+	return n;
+}
+
+// Function to check whether the given number is
+// Armstrong number or not
+bool isArmstrong(int x)
+{
+	// Calling order function
+	int n = order(x);
+	int temp = x, sum = 0;
+	while (temp) {
+		int r = temp % 10;
+		sum += power(r, n);
+		temp = temp / 10;
+	}
+
+	// If satisfies Armstrong condition
+	return (sum == x);
+}
+
+// Driver Program
+int main()
+{
+	int x = 153;
+	cout << boolalpha << isArmstrong(x) << endl;
+	x = 1253;
+	cout << boolalpha << isArmstrong(x) << endl;
+	return 0;
+}