diff --git a/computer_oriented_statistical_methods/Secant_method.CPP b/computer_oriented_statistical_methods/secant_method.cpp
similarity index 100%
rename from computer_oriented_statistical_methods/Secant_method.CPP
rename to computer_oriented_statistical_methods/secant_method.cpp
diff --git a/computer_oriented_statistical_methods/successive_approximation.CPP b/computer_oriented_statistical_methods/successive_approximation.cpp
similarity index 100%
rename from computer_oriented_statistical_methods/successive_approximation.CPP
rename to computer_oriented_statistical_methods/successive_approximation.cpp
diff --git a/math/prime_factorization.cpp b/math/prime_factorization.cpp
index bd1b99d97..c018de666 100644
--- a/math/prime_factorization.cpp
+++ b/math/prime_factorization.cpp
@@ -2,13 +2,12 @@
 #include <cstring>
 #include <iostream>
 #include <vector>
-using namespace std;
 
 // Declaring variables for maintaing prime numbers and to check whether a number
 // is prime or not
 bool isprime[1000006];
-vector<int> prime_numbers;
-vector<pair<int, int>> factors;
+std::vector<int> prime_numbers;
+std::vector<std::pair<int, int>> factors;
 
 // Calculating prime number upto a given range
 void SieveOfEratosthenes(int N) {
@@ -43,7 +42,7 @@ void prime_factorization(int num) {
             number = number / prime_numbers[i];
         }
 
-        if (count) factors.push_back(make_pair(prime_numbers[i], count));
+        if (count) factors.push_back(std::make_pair(prime_numbers[i], count));
     }
 }
 
@@ -52,9 +51,9 @@ void prime_factorization(int num) {
 */
 int main() {
     int num;
-    cout << "\t\tComputes the prime factorization\n\n";
-    cout << "Type in a number: ";
-    cin >> num;
+    std::cout << "\t\tComputes the prime factorization\n\n";
+    std::cout << "Type in a number: ";
+    std::cin >> num;
 
     SieveOfEratosthenes(num);
 
@@ -62,7 +61,7 @@ int main() {
 
     // Prime factors with their powers in the given number in new line
     for (auto it : factors) {
-        cout << it.first << " " << it.second << endl;
+        std::cout << it.first << " " << it.second << std::endl;
     }
 
     return 0;
diff --git a/others/GCD_of_n_numbers.cpp b/others/GCD_of_n_numbers.cpp
index b592e5931..37e82173a 100644
--- a/others/GCD_of_n_numbers.cpp
+++ b/others/GCD_of_n_numbers.cpp
@@ -5,7 +5,7 @@ int main() {
     int n;
     std::cout << "Enter value of n:" << std::endl;
     std::cin >> n;
-    int a[n];
+    int *a = new int[n];
     int i, j, gcd;
     std::cout << "Enter the n numbers:" << std::endl;
     for (i = 0; i < n; i++) std::cin >> a[i];
@@ -18,5 +18,6 @@ int main() {
             gcd = a[j] % gcd;  // calculating GCD by division method
     }
     std::cout << "GCD of entered n numbers:" << gcd;
+    delete[] a;
     return 0;
 }
diff --git a/others/fibonacci_fast.cpp b/others/fibonacci_fast.cpp
index dd3481422..381a82d7c 100644
--- a/others/fibonacci_fast.cpp
+++ b/others/fibonacci_fast.cpp
@@ -9,7 +9,6 @@
 
 #include <cstdio>
 #include <iostream>
-using namespace std;
 
 const long long MAX = 93;
 
@@ -31,7 +30,7 @@ long long fib(long long n) {
 int main() {
     // Main Function
     for (long long i = 1; i < 93; i++) {
-        cout << i << " th fibonacci number is " << fib(i) << "\n";
+        std::cout << i << " th fibonacci number is " << fib(i) << "\n";
     }
     return 0;
 }