chore: import upstream snapshot with attribution

math/finding_number_of_digits_in_a_number.cpp

@@ -0,0 +1,103 @@
+/**
+ * @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). The code for that is also included
+ * (finding_number_of_digits_in_a_number_using_log). 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 <cmath>     /// for log calculation
+#include <cstdint>
+#include <iostream>  /// for IO operations
+
+/**
+ * @brief The main function that checks
+ * the number of digits in a number.
+ * TC : O(number of digits)
+ * @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 This function finds the number of digits
+ * in constant time using logarithmic function
+ * TC: O(1)
+ * @param n the number to check its digits
+ * @returns the digits count
+ */
+double finding_number_of_digits_in_a_number_using_log(double n) {
+    // log(0) is undefined
+    if (n == 0) {
+        return 0;
+    }
+
+    // to handle the negative numbers
+    if (n < 0) {
+        n = -n;
+    }
+
+    double count = floor(log10(n) + 1);
+
+    return count;
+}
+
+/**
+ * @brief Self-test implementations
+ * @returns void
+ */
+static void first_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);
+}
+
+static void second_test() {
+    assert(finding_number_of_digits_in_a_number_using_log(5492) == 4);
+    assert(finding_number_of_digits_in_a_number_using_log(-0) == 0);
+    assert(finding_number_of_digits_in_a_number_using_log(10000) == 5);
+    assert(finding_number_of_digits_in_a_number_using_log(9) == 1);
+    assert(finding_number_of_digits_in_a_number_using_log(100000) == 6);
+    assert(finding_number_of_digits_in_a_number_using_log(13) == 2);
+    assert(finding_number_of_digits_in_a_number_using_log(564) == 3);
+}
+/**
+ * @brief Main function
+ * @returns 0 on exit
+ */
+int main() {
+    // run self-test implementations
+    first_test();
+    second_test();
+    std::cout << "All tests have successfully passed!\n";
+    return 0;
+}