MathLink C Function

MLNextPacket()

int MLNextPacket(MLINK link)
goes to the next packet on link and returns a constant to indicate its head.

The following packets can be returned:

BEGINDLGPKT	BeginDialogPacket[integer]	start a dialog subsession referenced by integer
CALLPKT	CallPacket[integer,list]	request to invoke the external function numbered integer with arguments list
DISPLAYENDPKT	DisplayEndPacket[]	obsolete PostScript graphics-related packet
DISPLAYPKT	DisplayPacket[]	obsolete PostScript graphics-related packet
ENDDLGPKT	EndDialogPacket[integer]	end the dialog subsession referenced by integer
ENTEREXPRPKT	EnterExpressionPacket[expr]	evaluate expr
ENTERTEXTPKT	EnterTextPacket[string]	parse string and evaluate as an expression
EVALUATEPKT	EvaluatePacket[expr]	evaluate expr while avoiding the kernel main loop
INPUTNAMEPKT	InputNamePacket[string]	name to be assigned to the next input (usually In[n]:=)
INPUTPKT	InputPacket[]	prompt for input, as generated by Mathematica's Input[] function
INPUTSTRPKT	InputStringPacket[]	request input as a string
MENUPKT	MenuPacket[integer,string]	menu request with title string
MESSAGEPKT	MessagePacket[symbol,string]	Mathematica message identifier (symbol::string)
OUTPUTNAMEPKT	OutputNamePacket[string]	name to be assigned to the next output (usually Out[n]=)
RESUMEPKT	ResumePacket[]	obsolete packet
RETURNEXPRPKT	ReturnExpressionPacket[expr]	result of EnterExpressionPacket[] evaluation
RETURNPKT	ReturnPacket[expr]	result of a calculation
RETURNTEXTPKT	ReturnTextPacket[string]	formatted text representation of a result
SUSPENDPKT	SuspendPacket[]	obsolete packet
SYNTAXPACKET	SyntaxPacket[integer]	position at which a syntax error was detected in the input line
TEXTPACKET	TextPacket[string]	text output from Mathematica, as produced by Print[]

MLNextPacket() returns ILLEGALPKT in the event of an error. mathlink.h defines ILLEGALPKT as 0.

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

EXAMPLES

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Basic Examples (1)

#include "mathlink.h"

/* read the type of the incoming packet on a link */

void f(MLINK lp)
{
    switch(MLNextPacket(lp))
    {
        case CALLPKT:
            /* read the CallPacket[] */
            break;
        case EVALUATEPKT:
            /* read the EvaluatePacket[] */
            break;
        case RETURNPKT:
            /* read the EvaluatePacket[] */

        /* ... */

        case ILLEGALPKT:
            /* unable to read the next packet from lp */
    }    
}