Create a constant unusedPartType object instead of recreating it each time

gptcl.cc

@@ -375,7 +375,7 @@ int GPTDataCL::DoOptions(int argc, char* argv[]) {
                      partNum = newPartNum;
                   if ((partNum >= 0) && (partNum < (int) GetNumParts())) {
                      typeHelper = GetString(typeCode, 2);
-                     if ((typeHelper != (GUIDData) "00000000-0000-0000-0000-000000000000") &&
+                     if ((typeHelper != PartType::unusedPartType) &&
                          (ChangePartType(partNum, typeHelper))) {
                         saveData = 1;
                         } else {

gptpart.cc

@@ -434,7 +434,7 @@ void GPTPart::ReversePartBytes(void) {
 void GPTPart::ChangeType(void) {
    string line;
    int changeName;
-   PartType tempType = (GUIDData) "00000000-0000-0000-0000-000000000000";
+   PartType tempType = PartType::unusedPartType;
 
 #ifdef USE_UTF16
    changeName = (GetDescription() == GetUTypeName());
@@ -454,7 +454,7 @@ void GPTPart::ChangeType(void) {
          else
             tempType = line;
       } // if/else
-   } while (tempType == (GUIDData) "00000000-0000-0000-0000-000000000000");
+   } while (tempType == PartType::unusedPartType);
    partitionType = tempType;
    cout << "Changed type of partition to '" << partitionType.TypeName() << "'\n";
    if (changeName) {

parttypes.cc

@@ -19,6 +19,7 @@ using namespace std;
 int PartType::numInstances = 0;
 AType* PartType::allTypes = NULL;
 AType* PartType::lastType = NULL;
+const PartType PartType::unusedPartType = (GUIDData) "00000000-0000-0000-0000-000000000000";
 
 // Constructor. Its main task is to initialize the data list, but only
 // if this is the first instance, since it's a static linked list.

parttypes.h

@@ -36,6 +36,9 @@ protected:
    static AType* lastType; // Pointer to last entry in the list
    void AddAllTypes(void);
 public:
+   // PartType with GUID "00000000-0000-0000-0000-000000000000"
+   static const PartType unusedPartType;
+
    PartType(void);
    PartType(const PartType & orig);
    PartType(const GUIDData & orig);