moved some snippets from C++ to C

Author: ashukr07

snippets/cpp/math-and-numbers/check-perfect-number.md renamed to snippets/c/mathematical-functions/check-perfect-number.md

@@ -5,18 +5,24 @@ tags: math, perfect-number
 author: ashukr07
 ---
 
-```cpp
+```c
+#include <stdbool.h>
+
+// Function to check if a number is a perfect number
 bool is_perfect(int n) {
+    if (n <= 1) return false;
+
     int sum = 1; // 1 is a divisor for all n > 1
     for (int i = 2; i * i <= n; ++i) {
         if (n % i == 0) {
             sum += i;
             if (i != n / i) sum += n / i;
         }
     }
-    return sum == n && n != 1;
+    return sum == n;
 }
 
-// Usage:
+// Usage
 is_perfect(28); // Returns: true
+is_perfect(12); // Returns: false
 ```

snippets/cpp/math-and-numbers/compound-interest.md renamed to snippets/c/mathematical-functions/compound-interest.md

@@ -5,17 +5,19 @@ tags: math, finance
 author: ashukr07
 ---
 
-```cpp
-#include <cmath>
+```c
+#include <math.h>
 
+// Function to calculate compound interest
 double compound_interest(double principal, double rate, double time, int n) {
-    return principal * std::pow(1 + rate / n, n * time);
+    return principal * pow(1 + rate / n, n * time);
 }
 
 // Usage:
 double principal = 1000.0;  // Initial amount
 double rate = 0.05;         // Annual interest rate (5%)
 double time = 2;            // Time in years
 int n = 4;                  // Compounded quarterly
+
 compound_interest(principal, rate, time, n); // Returns: 1104.081632653061
 ```

snippets/cpp/math-and-numbers/fibonacci-number.md renamed to snippets/c/mathematical-functions/fibonacci-number.md

@@ -5,7 +5,8 @@ tags: math, fibonacci, recursion
 author: ashukr07
 ---
 
-```cpp
+```c
+// Function to calculate the nth Fibonacci number
 int fibonacci(int n) {
     if (n <= 1) return n;
     return fibonacci(n - 1) + fibonacci(n - 2);

snippets/cpp/math-and-numbers/sum-of-digits.md renamed to snippets/c/mathematical-functions/sum-of-digits.md

@@ -5,7 +5,8 @@ tags: math, digits
 author: ashukr07
 ---
 
-```cpp
+```c
+// Function to calculate the sum of the digits of an integer
 int sum_of_digits(int n) {
     int sum = 0;
     while (n != 0) {