C++ Caesar Cipher

Caesars-Cipher/caesar-cipher.cpp

@@ -0,0 +1,47 @@
+#include <iostream>
+#include <string>
+
+using namespace std;
+
+void caesarShift(string& phrase, int shiftAmount);
+
+int main() {
+
+    string phrase;
+    int shiftAmount;
+
+    // Get the shift parameters
+
+    cout << "Enter your phrase: ";
+    getline(cin, phrase);
+
+    cout << "Enter your shift amount: ";
+    cin >> shiftAmount;
+
+    caesarShift(phrase, shiftAmount);
+
+    cout << endl << phrase;
+
+    return 0;
+}
+
+void caesarShift(string& phrase, int shiftAmount) {
+    // Caesar Shift a certain phrase by a certain amount
+
+    int normalizedAmount = shiftAmount % 26;  // Ensure that the shiftAmount keeps letters between a-z
+
+    for (int i = 0; i < phrase.length(); i++) {  // Shift each letter
+
+        if (phrase[i] >= 65 && phrase[i] <= 90 && phrase[i] + normalizedAmount > 90)  // Uppercase overflow
+            phrase[i] = phrase[i] + normalizedAmount - 26;
+
+        else if (phrase[i] >= 97 && phrase[i] <= 122 && phrase[i] + normalizedAmount > 122)  // Lowercase overflow
+            phrase[i] = phrase[i] + normalizedAmount - 26;
+
+        else if (!(phrase[i] >= 65 && phrase[i] <= 90) && !(phrase[i] >= 97 && phrase[i] <= 122))  // Leave all non-letter characters as they are
+            continue;
+
+        else
+            phrase[i] = phrase[i] + normalizedAmount;
+    }
+}