Add defensive programming to toPounds function for input validation

Author: Darkidd77

Sprint-2/3-mandatory-implement/3-to-pounds.js

@@ -4,3 +4,40 @@
 // You will need to declare a function called toPounds with an appropriately named parameter.
 
 // You should call this function a number of times to check it works for different inputs
+
+function toPounds(penceString) {
+    // return the price in pounds
+
+    // I took the code and made it as a function called toPounds with a parameter called penceString,
+    // but after reviewing the code in Ai I noticed i have to add something called defensive programming,
+    // to make sure the input is following the format of a string with a number followed by the letter p,
+    //  so I will add an if statement to check if the input is valid and if not, using endWith() method and then return an error message.
+
+    
+    if (!penceString.endsWith("p")) {
+    return "Error: Please enter a valid pence format (e.g., '399p')";
+}
+
+    const penceStringWithoutTrailingP = penceString.substring(
+  0,
+  penceString.length - 1
+);
+
+const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+
+const pounds = paddedPenceNumberString.substring(
+  0,
+  paddedPenceNumberString.length - 2
+);
+
+const pence = paddedPenceNumberString
+  .substring(paddedPenceNumberString.length - 2)
+  .padEnd(2, "0");
+
+return (`£${pounds}.${pence}`);
+}
+
+console.log(toPounds("399p"));
+console.log(toPounds("5p"));
+console.log(toPounds("abc"));
+