feat: Finding no. of digits in a Number (#1497)

* Finding no. of digits in a Number

* Initialize n

* Initialize n as int

* Changes done

* Changes done with codes by adding more comments

* Changes done with codes by adding name as md

* Modified comments

* add void

* remove void & update comments

* Set some changes to pass Awesome CI Workflow

* add return 0 & file name in lower case

* Changes done..

* Update finding_number_of_Digits_in_a_Number.cpp

* Update finding_number_of_Digits_in_a_Number.cpp

* Update finding_number_of_Digits_in_a_Number.cpp

* formatting filenames 0ec45e33

* updating DIRECTORY.md

* clang-format and clang-tidy fixes for 0ec45e33

* clang-format and clang-tidy fixes for 9c0a437e

* updating DIRECTORY.md

* Wrote test, needs review

* [fix/docs]: Fix tests/code and add documentation

Co-authored-by: David Leal <halfpacho@gmail.com>
Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>

math/finding_number_of_digits_in_a_number.cpp

@@ -0,0 +1,66 @@
+/**
+ * @author [aminos 🇮🇳](https://github.com/amino19)
+ * @file
+ *
+ * @brief [Program to count digits
+ * in an
+ * integer](https://www.geeksforgeeks.org/program-count-digits-integer-3-different-methods)
+ * @details It is a very basic math of finding number of digits in a given
+ * number i.e, we can use it by inputting values whether it can be a
+ * positive/negative value, let's say: an integer. There is also a second
+ * method: by using "K = floor(log10(N) + 1)", but it's only applicable for
+ * numbers (not integers).
+ * For more details, refer to the
+ * [Algorithms-Explanation](https://github.com/TheAlgorithms/Algorithms-Explanation/blob/master/en/Basic%20Math/Finding
+ * the number of digits in a number.md) repository.
+ */
+
+#include <cassert>   /// for assert
+#include <iostream>  /// for IO operations
+
+/**
+ * @brief The main function that checks
+ * the number of digits in a number.
+ * @param n the number to check its digits
+ * @returns the digits count
+ */
+uint64_t finding_number_of_digits_in_a_number(uint64_t n) {
+    uint64_t count = 0;  ///< the variable used for the digits count
+
+    // iterate until `n` becomes 0
+    // remove last digit from `n` in each iteration
+    // increase `count` by 1 in each iteration
+    while (n != 0) {
+        // we can also use `n = n / 10`
+        n /= 10;
+        // each time the loop is running, `count` will be incremented by 1.
+        ++count;
+    }
+
+    return count;
+}
+
+/**
+ * @brief Self-test implementations
+ * @returns void
+ */
+static void test() {
+    assert(finding_number_of_digits_in_a_number(5492) == 4);
+    assert(finding_number_of_digits_in_a_number(-0) == 0);
+    assert(finding_number_of_digits_in_a_number(10000) == 5);
+    assert(finding_number_of_digits_in_a_number(9) == 1);
+    assert(finding_number_of_digits_in_a_number(100000) == 6);
+    assert(finding_number_of_digits_in_a_number(13) == 2);
+    assert(finding_number_of_digits_in_a_number(564) == 3);
+
+    std::cout << "All tests have successfully passed!\n";
+}
+
+/**
+ * @brief Main function
+ * @returns 0 on exit
+ */
+int main() {
+    test();  // run self-test implementations
+    return 0;
+}