Why is the compiler throwing this warning: "missing initializer"? Isn't the structure initialized?

I'm creating some sort of frontend for a program. To launch the program I'm using the call CreateProcess(), which among other things receives a pointer to a STARTUPINFO structure. To initialize the structure I used to do:

STARTUPINFO startupInfo = {0}; // Or even '\0'.
startupInfo.cb = sizeof(startupInfo);

When compiling the program with GCC enabling these sets of warnings -Wall -Wextra it gives me a warning saying that there's a missing initializer pointing to the first line.

warning: missing initializer
warning: (near initialization for 'startupInfo.lpReserved')

So I ended up doing:

STARTUPINFO startupInfo;
memset(&startupInfo, 0, sizeof(startupInfo));
startupInfo.cb = sizeof(startupInfo);

And this way the compiler doesn't give any warning. The question is, what is the difference between these ways of initializing a structure? Using the first method, isn't the structure initialized? Which one would you recommend?