Question

Can a C pre-processsor macro be used to generate the string below where size is the result of the sizeof macro?

const char testXmlElement [] = "< xs:element name="count" size="4" \>";

Use of the stringizing macro generates the result size=”sizeof(int)” instead of the desired result, size=”4″.

#define xstr(s) str(s)
#define str(s) #s
const char testXmlElement[] =
"<element size=\"" 
xstr(sizeof(int))
"\""
" \\>";

My intention was to create an XML schema in an embedded microcontroller application using both the sizeof() and offsetof() macros. The resulting schema would be used to de-serialize XML to nested C data structures.

Thanks in advance,

Answer 1

I don’t believe so. The preprocessor runs before the compiler, and sizeof is interpreted by the compiler.