Finished problem 2

.gitignore

@@ -1,3 +1,4 @@
 *.dat
 *.class
 /TAGS
+*.txt

StackApps.java

@@ -3,31 +3,62 @@
 
 import java.util.Scanner;
 
-public class StackApps 
-{    
+public class StackApps
+{
     // convert a decimal number into a binary number and save it in a stack
     // Do not create any arrays! Do not use any Java libraries to do the convertion.
     // Doing so will result in points deduction.
     public String decToBin(int numDec)
     {
         CharStack stackBinary = new CharStack(64);  // stack used to store the result binary number
-        
-        // TODO: complete this method
-        
-        return stackBinary.toString();  // return a string representation of the stack
+        while (numDec > 0) {
+	    if (numDec % 2 == 0)
+		stackBinary.push('0');
+	    else
+		stackBinary.push('1');
+	    numDec /= 2;
+	}
+           return stackBinary.toString();  // return a string representation of the stack
     }
-    
+
     // compute the sum of the two big intergers and save the result in a stack
     // Do not create any arrays! Do not use any Java libraries to do the calculation.
     // Doing so will result in points deduction.
     public String addBigIntegers(String num1, String num2)
     {
+
         CharStack stackNum1 = new CharStack(64);    // stack used to store number 1
         CharStack stackNum2 = new CharStack(64);    // stack used to store number 2
         CharStack stackResult = new CharStack(64);  // stack used to store the result of the addition
-        
-        // TODO: complete this method
-        
+        CharStack remaining;
+	for (int i = 0; i < num1.length(); i += 1)
+	    stackNum1.push(num1.charAt(i));
+	for (int i = 0; i < num2.length(); i += 1)
+	    stackNum2.push(num2.charAt(i));
+
+	int carry = 0;
+	int a;
+	int b;
+	int result;
+	while (!(stackNum1.isEmpty() || stackNum2.isEmpty())) {
+	    a = (int) (stackNum1.pop() - '0');
+	    b = (int) (stackNum2.pop() - '0');
+	    result = (a+b+carry);
+	    carry = result/10;
+	    stackResult.push((char)((result%10) +  '0'));
+	}
+	if (stackNum1.isEmpty())
+	    remaining = stackNum2;
+	else
+	    remaining = stackNum1;
+	while (!(remaining.isEmpty())) {
+	    a = (int) (remaining.pop() - '0');
+	    result = (a+carry);
+	    carry = result/10;
+	    stackResult.push((char)((result%10) + '0'));
+	}
+	if (carry > 0)
+	    stackResult.push((char)(carry + '0'));
         return stackResult.toString();  // return a string representation of the stack
-    }    
+    }
 }