The variable timeOld is being used without being initialized in c++

Question

char* timeNew = _com_util::ConvertBSTRToString(cpi->getTime());
if(timeFirst == true)
    {
    strcpy(timeOld,timeNew);
    timeFirst = false;
    }

how can I initiliase timeold if I dont know what the size of character array returned by cpi->getTime is?

Prefer `if(timeFirst)`. The text `== true` is unnecessary and redundant. And redundant. — Robᵩ, Mar 12 '12 at 15:45
@Rob: Yes, and it's redundant too! You could just as well use `if ((timeFirst == true) == true)` — Fred Larson, Mar 12 '12 at 15:48
You've asked this question before! http://stackoverflow.com/questions/7769998/how-to-return-char-array-in-c — MSalters, Mar 12 '12 at 15:56
BTW: [How to: Convert Between Various (Microsoft) String Types](http://msdn.microsoft.com/en-us/library/ms235631(VS.80).aspx) — MSalters, Mar 12 '12 at 16:03

hmjd · Accepted Answer · 2012-03-12T15:27:11.193

Allocate memory for it based on length of timeNew:

delete[] timeOld;
timeOld = new char[strlen(timeNew) + 1];

or you could make timeOld a std::string and let it manage memory for you:

std::string timeOld;

timeOld = timeNew; // If timeNew is dynamically allocated you must still
                   // delete[] it when no longer required, as timeOld
                   // takes a copy of timeNew, not ownership of timeNew.

You can access the const char* using std::string::c_str() if really required.

score 1 · Answer 2 · answered Mar 12 '12 at 15:23

Use strings where possible:

char *t= _com_util::ConvertBSTRToString(cpi->getTime());
std::string timeNew(t);
delete[] t;
if(timeFirst == true)
{
     timeOld=timeNew;
     timeFirst = false;
 }

if you don't have to manage the memory returned by teh function simply:

std::string timeNew(_com_util::ConvertBSTRToString(cpi->getTime()));
if(timeFirst == true)
{
     timeOld=timeNew;
     timeFirst = false;
 }

score 0 · Answer 3 · answered Mar 12 '12 at 15:49

If you have to use ConvertBSTRToString then use boost::scoped_array<char> or boost::shared_array<char> to ensure you get clean-up.

boost::shared_array<char> time;
time.reset( _com_util::ConvertBSTRtoString( cpi->getTime() );

automatically reallocates. No calls to delete or delete[] necessary.

The variable timeOld is being used without being initialized in c++

3 Answers3