Why doesn't %zd printf format work in VS2010?

Question

Following piece of my code does not print the value in visual studio.

int main() { 
    intptr_t P = 10;
    printf("test value is %zd",P);
    return 0;
}

OUTPUT:

test value is zd

I expect the the above code print

test value is 10

i am using intptr_t instead of integer so as to make the code to adjust in both the 32 bit and 64 bit architecture.

Answer 1

The z prefix isn't defined in Microsoft's version of printf. I think the I prefix might work. See http://msdn.microsoft.com/en-us/library/tcxf1dw6.aspx

Answer 2

Although the z length specifier is supported in C99, Visual Studio 2010 does not support C99, and instead conforms to an older version of C that was missing the z length specifier. As an extension, VS2010 does support the I length specifier instead for size_t, but this is not portable to other platforms.

I would recommend using an unsigned long long with the %llu specifier instead; the overhead is minimal and it's portable to C99 platforms as well.