fixed warnings and errors before moving to abs_sub for integer.cpp

integer.cpp

@@ -88,10 +88,14 @@ public:
     }
 
     auto idx = true_lhs_size - 1;
-    while (idx >= 0) {
+    while (true) {
       if (lhs.bytes[idx] != rhs.bytes[idx]) {
         return lhs.bytes[idx] < rhs.bytes[idx];
       }
+      if (idx == 0) {
+        break;
+      }
+      idx--;
     }
     return false;
   }
@@ -149,7 +153,7 @@ public:
     Integer tmp = std::move(lhs);
     Integer tmp_r = rhs;
     lhs = 0;
-    while (tmp_r > 0) {
+    while (tmp_r > Integer{0}) {
       lhs += tmp;
       tmp_r -= 1;
     }
@@ -230,8 +234,8 @@ public:
 
     Integer discard = rhs;
     std::stringstream to_output{};
-    while (discard != 0) {
-      to_output << discard % 10;
+    while (discard != Integer{0}) {
+      to_output << discard % static_cast<byte>(10);
       discard /= 10;
     }
     std::string out;
@@ -241,7 +245,7 @@ public:
     return lhs;
   }
 
-  explicit operator unsigned long() {
+  operator unsigned long() {
     unsigned long ret = 0;
     for (std::size_t i = 0; i < std::min(size, sizeof(unsigned long)); i++) {
       ret += (static_cast<unsigned long>(this->bytes[i]) << (i * 8));