It's unlikely that the C function with the prototype you give is passing back a string. You're passing in a character buffer(as char*), and it doesn't know how long it is unless it already contains a null terminated string.

There are basically two ways to return a string in C: 

const char* fcn(void);

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returns a pointer to an internal buffer. More common (for functions such as read()) is 

int fcn(char *buffer, int bufsize);

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where bufsize is the size of the buffer, and the function returns the number of characters read. In this case, what you want to do is something like: 

const int bufsize = 16;
int len;
RETVAL = NEWSV(0,bufsize);

len = fcn(SvPV_nolen(RETVAL), bufsize);
SvCUR_set(RETVAL, len);

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The main problem I see with your code is you never find out the length of the string returned by fcn().

Ron Steinke rsteinke@w-link.net

In reply to Re: perl guts and the SvPV() macro by rsteinke
in thread perl guts and the SvPV() macro by mbr

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