chore(CPlusPlus): add reverse digits (#492)

algorithms/CPlusPlus/Maths/reverse-digits.cpp

@@ -0,0 +1,47 @@
+/*
+Description: A program to reverse the digits of a number.
+
+Approach: Running a while loop over number till it becomes 0
+Multiplying the result variable to 10 each time.
+Taking the modulus of number at every iteration and adding it to the final result to generate the reverse.
+Dividing the number by 10 at every iteration.
+*/
+
+#include <iostream>
+using namespace std;
+
+//function
+long reverse_digit(long n)
+{
+    //result variable
+    long num = 0;
+    while (n != 0)
+    {
+        //storing the last digit of n in temp variable
+        long temp = n % 10;
+        //multiplying the num variable into 10 and adding temp value to it
+        num = num * 10 + temp;
+        //Dividing n by 10 at each iteration
+        n = n / 10;
+    }
+    return num;
+}
+
+//main starts
+int main()
+{
+    cout << "Enter a number\n";
+    long n;
+    cin >> n;
+    cout << "Reverse number is: ";
+    cout << reverse_digit(n);
+}
+
+/*
+Input: 
+Enter a number
+1234
+
+Output:
+Reverse number is: 4321
+*/

algorithms/CPlusPlus/README.md

@@ -123,6 +123,7 @@
 3. [Prime Sieve](Maths/prime-sieve.cpp)
 4. [Fibonacci Series](Maths/fibonaccci-series.cpp)
 5. [Armstrong Number](Maths/armstrong.cpp)
+6. [Reverse digit of a number](Maths/reverse-digits.cpp)
 
 # Recursion