From 042acb10595161ac36b47768f7c1e58c553e6b33 Mon Sep 17 00:00:00 2001
From: Michael Abed <michaelabed@gmail.com>
Date: Sun, 12 Feb 2012 15:42:43 -0500
Subject: solve problem 4

---
 Makefile |  5 ++++-
 Q4.cpp   | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index cce7ed3..1a7e44c 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 
-all: Q1 Q2 Q3
+all: Q1 Q2 Q3 Q4
 
 Q1: Q1.cpp
 	g++ -o Q1 Q1.cpp
@@ -10,5 +10,8 @@ Q2: Q2.cpp
 Q3: Q3.cpp
 	g++ -o Q3 Q3.cpp
 
+Q4: Q4.cpp
+	g++ -o Q4 Q4.cpp
+
 clean:
 	rm Q1 Q2 Q3
diff --git a/Q4.cpp b/Q4.cpp
index e69de29..0a14cad 100644
--- a/Q4.cpp
+++ b/Q4.cpp
@@ -0,0 +1,49 @@
+/*
+ * Michael Abed <mgabed@bu.edu>
+ *
+ * Lab 1 Problem 4
+ *
+ * Convert a letter based on an offset. 
+ */
+
+#include <iostream>
+
+using namespace std;
+
+int main()
+{
+    
+    char input;
+    int offset;
+    int caseswap = 'a' - 'A';
+
+    cout << "Enter character: ";
+    cin >> input; // any character will do
+
+    do { // validate input
+        cout << "Offset (enter 0 to convert case): ";
+        cin >> offset;
+        if (offset < 0)
+            cout << "Offset must be positive" << endl;
+        if (offset >= 128)
+            cout << "Offset must be less than 128" << endl;
+    } while (offset < 0 || offset >= 128);
+    
+    char knew;
+    // calculate new character
+    if (offset == 0 && input >= 'A' && input <= 'Z')
+        knew = input + caseswap;
+    else if (offset == 0 && input >= 'a' && input <= 'z')
+        knew = input - caseswap;
+    else if (offset == 0)
+        knew = input;
+    else
+        knew = input + offset;
+    
+    if (input + offset > '~' ) // larger is non printing
+        cout << "Result outside of ASCII range" << endl;
+    else
+        cout << "New character: " << knew << endl;
+
+    return 0;
+}
-- 
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