Add some error handling

README.md

@@ -1,4 +1,8 @@
 # lychrel
 Iterate through numbers to rule out that they are lychrel numbers
 
+compile with: g++ -o lychrel lychrel.cpp lychrel.hpp main.cpp 
+
+run with: ./lychrel <a number you want to check>
+
 https://en.wikipedia.org/wiki/Lychrel_number

lychrel.cpp

@@ -1,5 +1,6 @@
 #include <iostream>
 #include <cstring>
+#include <climit>
 #include "lychrel.hpp"
 
 long long get_len (string a, string b) {
@@ -14,7 +15,7 @@ string add (string a, string b) {
     
     char result[len + 2] = { '0' };
 
-    if(len == -1) {
+    if(len == -1 or len == LLONG_MAX) {
         return "-1";
     } else {
 	int reg = 0;

main.cpp

@@ -1,5 +1,6 @@
 #include <iostream>
 #include <cstring>
+#include <climits>
 #include "lychrel.hpp"
 
 
@@ -8,16 +9,23 @@ int main(int argc, char **argv)
     string a = argv[1];
     string b(a.rbegin(),a.rend());
     string added = add(a,b);
+    if(added == "-1") {
+	cerr << "ERROR: adding error detected, we might have reached the end of our datatype or some how the two numbers don't have the same legth\n";
+        return 1;
+    }
     long long it = 0;
     do {
         cout << "Iteration " << ++it << " currently working on " << added <<  endl;	
 	a = added;
         b = string(a.rbegin(),a.rend());
         added = add(a,b);
-    } while(! is_palindrome(added) );
+            if(added == "-1") {
+	        cerr << "ERROR: adding error detected, we might have reached the end of our datatype or some how the two numbers don't have the same legth\n";
+                return 1;
+	    }
+        } while(! is_palindrome(added));
     cout << "Iteration " << ++it << " currently working on " << added <<  endl;	
-    cout << "That consists of\n" << a << "\n+\n" << b << "\nand that it is a palindrome." << endl;	
+    cout << "That consists of\n" << a << "\n+\n" << b << "\nand that it " << (is_palindrome(added) ? "is" : "is not") << " a palindrome." << endl;	
-
 
     return 0;
 }