Initializing char buffer in c++

Question

I am writing application on c++ and using intel inspector to do memory profiling.

However i have a question about the various results that i got during my memory profiling test for finding potential memory problems.

I am trying to do a better stable application and i have few questions I know they are basics still at this time looking too much into the code i am kind of confused. Thank you for the help in getting them clarfied.

1. should i initialize char buffer[30] to a default value ?
2. what should be the default vaue for the LPWSTR (I tried NULL) still it complains uninitialized memory access on my member variable.
3. Initialize a struct. I tried using memset. Still the profiler looks unhappy and complains uninitialized memory access.

One instance is In my caller class constructor i have initialized the handle as

m_hidHandle = NULL; //member variable and an object of struct hid_device

After which i make a call to do hid_write.

And in there, hid_write which inturns calls writeFile (this is the api class hid.c)

WriteFile(dev->device_handle, buf, length, NULL, NULL);

Here i get a complain that uninitialized memory access. I even tried checking the api documentation for WrtieFile. Still unclean what i am making it to complain about a memory problem.

Another instance is I have a member variable

WINHTTP_CURRENT_USER_IE_PROXY_CONFIG m_pConfig;

In the constructor, I am trying to initialize the struct to NULL:

memset( &m_pConfig, 0, sizeof(WINHTTP_CURRENT_USER_IE_PROXY_CONFIG) );

It complained uninitialized memory access. I even tried

//proxyConfig.fAutoDetect = false;
//proxyConfig.lpszAutoConfigUrl = NULL;
//proxyConfig.lpszProxy = NULL;
//proxyConfig.lpszProxyBypass = NULL;

Still no help.

Answer 1

1: Use std::string and it will be default-initialized:

std::string s; //empty

Otherwise, char s[30] = {}; will fill it with 0s. std::string is much, much better for a stable application. If you need the C string to pass to an API, use c_str() to get a constant version. If you need a non-constant version, plop it into a vector of characters (which can be initialized with two iterators) and pass either &v[0] or v.data() .

2: NULL should work, as it's a wchar_t * (assuming the Windows API data type). If you have C++11, use nullptr instead.

3: memset is a terrible idea for any non-POD class. If you don't have a constructor, a default constructor will be provided for you that default-initializes all of the non-trivially constructible members. It's better to put in your own if you have members such as int , which would otherwise remain uninitialized:

struct S {
    int i;
    std::string s; //non-trivially constructible, so default-initialized
};

S s;

In the above example, you'll get an empty string and uninitialized int . That's why your own is usually better:

S() : i(), s() {}