Update 'converter.cpp'

do while instead of while, want loop to run at least once.

converter.cpp

@@ -1,5 +1,5 @@
 #include <iostream>
-
+#include <iomanip>
 using namespace std;
 
 
@@ -7,18 +7,23 @@ using namespace std;
 
 void Menu(){ // <- The menu is (mostly) static, no need for it to be in main
     cout << "Simple temperature converter \n";
-    cout << "Conversion options \n [1]C to F \n [2]F to C \n [3]Quit" << endl;
-    cout << "Select option [1-3]: ";
+    cout << "Conversion options \n [1]C to F \n [2]F to C \n [3]F to K \n [4]C to K \n [5]Quit" << endl;
+    cout << "Select option [1-5]: ";
 }
 
-double C, F;
+double C, F, K;
+
+double convertC2K(double C, double K) {
+    K = (C + 273.15);
+    return(K);
+}
 
-double convertC(double C, double F){ // <- converts to Celsius
+double convertC(double C, double F) { // <- converts to Celsius
     C = (F - 32) / 1.8;
     return(C);
 }
 
-double convertF(double C, double F){ // <- converts to fahrenheit
+double convertF(double C, double F) { // <- converts to fahrenheit
     F = (C * 1.8) + 32;
     return(F);
 }
@@ -27,22 +32,28 @@ int main() {
     int input;
     Menu();
     cin >> input;
-
-    while (input != 3) {
-
+    do {
         if (input == 1) {
             cout << "Enter temperature in Celsius: ";
             cin >> input;
             C = input;
-            cout << convertF(C, F) << endl;
+            cout << setprecision(2) << convertF(C, F) << endl;
             break;
-        } else if (input == 2) {
+        } 
+        else if (input == 2) {
             cout << "Enter temperature in Fahrenheit: ";
             cin >> input;
             F = input;
-            cout << convertC(C, F);
+            cout << setprecision(2) << convertC(C, F) << endl;
             break;
         }
+        else if (input == 4) {
+            cout << "Enter temperature in Celsius: ";
+            cin >> input;
+            C = input;
+            cout << setprecision(2) << convertC2K << endl;
+        }
+        while (input != 4)
     }
     cout << "\nExiting...";
     return(0);