chore: use using-declaration

Author: MRDGH2821

C++ programs/task1.cpp

@@ -2,11 +2,10 @@
 // Write a C++ program to print ASCII value of a character.
 
 #include <iostream>
-using namespace std;
 
 int main() {
   char c;
-  cout << "Enter a character: ";
-  cin >> c;
-  cout << "ASCII Value is: " << int(c);
+  std::cout << "Enter a character: ";
+  std::cin >> c;
+  std::cout << "ASCII Value is: " << int(c);
 }

C++ programs/task10.cpp

@@ -3,7 +3,6 @@
 
 #include <string.h>
 #include <iostream>
-using namespace std;
 
 char to_lowercase(char c) {
   if (c >= 'A' && c <= 'Z') {
@@ -14,12 +13,12 @@ char to_lowercase(char c) {
 }
 
 int main() {
-  string str;
-  cout << "Enter a string: ";
-  getline(cin, str);
+  std::string str;
+  std::cout << "Enter a string: ";
+  std::getline(std::cin, str);
   for (char& c : str) {
     c = to_lowercase(c);
   }
-  cout << str;
+  std::cout << str;
   return 0;
 }

C++ programs/task2.cpp

@@ -2,16 +2,15 @@
 // Write a C++ program to check if the given number is even or odd.
 
 #include <iostream>
-using namespace std;
 
 int main() {
   int no;
-  cout << "Enter a no.: ";
-  cin >> no;
+  std::cout << "Enter a no.: ";
+  std::cin >> no;
   if (no % 2 == 0) {
-    cout << "Even";
+    std::cout << "Even";
   } else {
-    cout << "Odd";
+    std::cout << "Odd";
   }
   return 0;
 }

C++ programs/task3.cpp

@@ -2,22 +2,21 @@
 // Write a C++ program to check if the given year is a leap year.
 
 #include <iostream>
-using namespace std;
 
 int main() {
   int year;
-  cout << "Enter a year: ";
-  cin >> year;
+  std::cout << "Enter a year: ";
+  std::cin >> year;
   if (year % 100 == 0) {
     if (year % 400 == 0) {
-      cout << "Century Leap year.\n";
+      std::cout << "Century Leap year.\n";
     } else {
-      cout << "Not a century leap year.\n";
+      std::cout << "Not a century leap year.\n";
     }
   } else if (year % 4 == 0) {
-    cout << "Leap year.\n";
+    std::cout << "Leap year.\n";
   } else {
-    cout << "Not a leap Year.\n";
+    std::cout << "Not a leap Year.\n";
   }
   return 0;
 }

C++ programs/task4.cpp

@@ -2,15 +2,14 @@
 // Write a C++ program to calculate sum of all the elements of an array.
 
 #include <iostream>
-using namespace std;
 
 int main() {
   int ar[10];
-  cout << "Enter 10 elements: " << endl;
+  std::cout << "Enter 10 elements: " << std::endl;
   int sum = 0;
   for (int i = 0; i < 10; i++) {
-    cin >> ar[i];
+    std::cin >> ar[i];
     sum += ar[i];
   }
-  cout << "Sum of array: " << sum;
+  std::cout << "Sum of array: " << sum;
 }

C++ programs/task5.cpp

@@ -2,13 +2,12 @@
 // Write a C++ program to find the largest and smallest element in an array.
 
 #include <iostream>
-using namespace std;
 
 int main() {
   int ar[10];
-  cout << "Enter 10 elements: " << endl;
+  std::cout << "Enter 10 elements: " << std::endl;
   for (int i = 0; i < 10; i++) {
-    cin >> ar[i];
+    std::cin >> ar[i];
   }
   int large = 0, small = 99999;
   for (int i = 0; i < 10; i++) {
@@ -20,6 +19,6 @@ int main() {
       small = ar[i];
     }
   }
-  cout << "Largest number:" << large << endl
-       << "Smallest number:" << small << endl;
+  std::cout << "Largest number:" << large << std::endl
+            << "Smallest number:" << small << std::endl;
 }

C++ programs/task6.cpp

@@ -2,7 +2,6 @@
 // Write a C++ program to sort elements of array in ascending order.
 
 #include <iostream>
-using namespace std;
 
 int* bubbleSort(int a[]) {
   int temp;
@@ -20,13 +19,13 @@ int* bubbleSort(int a[]) {
 
 int main() {
   int ar[10];
-  cout << "Enter 10 elements: " << endl;
+  std::cout << "Enter 10 elements: " << std::endl;
   for (int i = 0; i < 10; i++) {
-    cin >> ar[i];
+    std::cin >> ar[i];
   }
   int* a = bubbleSort(ar);
-  cout << "Sorted array: " << endl;
+  std::cout << "Sorted array: " << std::endl;
   for (int i = 0; i < 10; i++) {
-    cout << a[i] << " ";
+    std::cout << a[i] << " ";
   }
 }

C++ programs/task7.cpp

@@ -2,7 +2,6 @@
 // Write a C++ program to swap two numbers using function.
 
 #include <iostream>
-using namespace std;
 
 void swap(int* a, int* b) {
   int temp;
@@ -13,12 +12,12 @@ void swap(int* a, int* b) {
 
 int main() {
   int q, w;
-  cout << "Enter 2 numbers: " << endl;
-  cin >> q >> w;
-  cout << "1st number = " << q << endl;
-  cout << "2nd number = " << w << endl;
+  std::cout << "Enter 2 numbers: " << std::endl;
+  std::cin >> q >> w;
+  std::cout << "1st number = " << q << std::endl;
+  std::cout << "2nd number = " << w << std::endl;
   swap(&q, &w);
-  cout << "After swapping:" << endl;
-  cout << "1st number = " << q << endl;
-  cout << "2nd number = " << w << endl;
+  std::cout << "After swapping:" << std::endl;
+  std::cout << "1st number = " << q << std::endl;
+  std::cout << "2nd number = " << w << std::endl;
 }

C++ programs/task8.cpp

@@ -13,14 +13,13 @@
 #include <stdio.h>
 #include <string.h>
 #include <iostream>
-using namespace std;
 
 int main() {
   char str1[20], str2[20];
   int len, len1, len2, i, j, found = 0, not_found = 0;
-  cout << "Enter first string :";
+  std::cout << "Enter first string :";
   fgets(str1, 20, stdin);
-  cout << "Enter second string :";
+  std::cout << "Enter second string :";
   fgets(str2, 20, stdin);
   len1 = strlen(str1);
   len2 = strlen(str2);
@@ -40,13 +39,13 @@ int main() {
       }
     }
     if (not_found == 1) {
-      cout << str1 << " and " << str2 << " are not anagrams.";
+      std::cout << str1 << " and " << str2 << " are not anagrams.";
     } else {
-      cout << str1 << " and " << str2 << " are anagrams.";
+      std::cout << str1 << " and " << str2 << " are anagrams.";
     }
   } else {
-    cout << str1 << " and " << str2
-         << " are not of same length to be anagrams.";
+    std::cout << str1 << " and " << str2
+              << " are not of same length to be anagrams.";
   }
   getch();
 }

C++ programs/task9.cpp

@@ -12,18 +12,17 @@
  */
 
 #include <iostream>
-using namespace std;
 
 int main() {
   int days, y, w, d;
-  cout << "Enter number of days: ";
-  cin >> days;
+  std::cout << "Enter number of days: ";
+  std::cin >> days;
   y = days / 365;
   days = days % 365;
   w = days / 7;
   days = days % 7;
   d = days;
-  cout << "Years: " << y << endl;
-  cout << "Weeks: " << w << endl;
-  cout << "Days : " << d << endl;
+  std::cout << "Years: " << y << std::endl;
+  std::cout << "Weeks: " << w << std::endl;
+  std::cout << "Days : " << d << std::endl;
 }