WSTestUTF16HeadWithArgCount (C Function)
int WSTestUTF16HeadWithArgCount(WSLINK l, const unsigned short *s, int v, int *n)
tests that the next object to be read from the WSTP connection specified by l is an expression with head s, an UTF-16 encoded character string of length v, and that the number of arguments of the expression is n.
Details
- WSTestUTF16HeadWithArgCount() fails if the current expression on the link is not a function with a symbol as a head, if the name of the symbol does not match s, or if the number of arguments for the function is not n.
- WSTestUTF16HeadWithArgCount() stores the actual number of arguments to the function in n when the function returns.
- The symbol s encoded as an UTF-16 string must begin with a byte order mark.
- The length of the symbol v must include the byte order mark.
- WSTestUTF16HeadWithArgCount() returns 0 in the event of an error, and a nonzero value if the function succeeds.
- Use WSError() to retrieve the error code if WSTestUTF16HeadWithArgCount() fails.
- WSTestUTF16HeadWithArgCount() will reset the stream pointer to the expression on the link just prior to calling WSTestUTF16HeadWithArgCount() if the function fails. This operation behaves as if the programmer has called WSCreateMark(l); WSTestUTF16HeadWithArgCount(...); WSSeekToMark(...).
- WSTestUTF16HeadWithArgCount() is declared in the WSTP header file wstp.h.
Examples
Basic Examples (1)
#include "wstp.h"
/* A function to test whether the next expression on the Link is Plus[a,b] */
void f(WSLINK l)
{
unsigned short symbol[5];
int args = 2;
const char *symbol;
symbol[0] = 0xFEFF;
symbol[1] = 'P';
symbol[2] = 'l';
symbol[3] = 'u';
symbol[4] = 's';
if(! WSTestUTF16HeadWithArgCount(l, (const unsigned short *)symbol, 5, &args))
{ /* Next expression is not Plus, or does not have two args */ }
if(! WSGetSymbol(l, &symbol))
{ /* Unable to read symbol */ }
/* Check if symbol is 'a' */
WSReleaseSymbol(l, symbol);
if(! WSGetSymbol(l, &symbol))
{ /* Unable to read symbol */ }
/* Check if the symbol is 'b' */
WSReleaseSymbol(l, symbol);
}