SEARCH MATHEMATICA 8 DOCUMENTATION

THIS IS DOCUMENTATION FOR AN OBSOLETE PRODUCT.
SEE THE DOCUMENTATION CENTER FOR THE LATEST INFORMATION.

Mathematica > MathLink C Language Functions >

MathLink C Function

MLTestHead()

int MLTestHead(MLINK link, const char *head, int *n)
tests that the next object to be read from link is an expression with head head, and stores the number of arguments of the expression in n.

MORE INFORMATION

MLTestHead() fails if the current object on the link is not a function with a symbol as a head, or if the name of the symbol does not match head.

MLTestHead() returns 0 in the event of an error, and a nonzero value if the function succeeds.

Use MLError() to retrieve the error code if MLTestHead() fails.

MLTestHead() is declared in the MathLink header file mathlink.h.

EXAMPLES

CLOSE ALL

Basic Examples (1)

#include "mathlink.h"

/* test whether the head of the incoming object is "ReturnPacket" */

void f(MLINK lp)
{
    int args;

    if(MLTestHead(lp, "ReturnPacket", &args))
        { /* read the contents of the ReturnPacket[] */ }
    else
        { /* the head of incoming packet is not "ReturnPacket" */ }
}