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XtSetArg, XtMergeArgLists - set and merge ArgLists


int XtSetArg(Arg arg, String name, XtArgVal value);
ArgList XtMergeArgLists(ArgList args1, Cardinal num_args1, ArgList
args2, Cardinal num_args2);


Specifies the name-value pair to set.

Specifies the first ArgList.

Specifies the second ArgList.

Specifies the number of arguments in the first argument list.

Specifies the number of arguments in the second argument list.

Specifies the name of the resource.

Specifies the value of the resource if it will fit in an XtArgVal or the address.


The XtSetArg function is usually used in a highly stylized manner to minimize the probability of making a mistake; for example:

0>=40 .vs 0u
0<=39 .vs 0p
Arg args[20];
int n;
n = 0;
XtSetArg(args[n], XtNheight, 100);    n++;
XtSetArg(args[n], XtNwidth, 200);    n++;
XtSetValues(widget, args, n);

Alternatively, an application can statically declare the argument list and use XtNumber:

0>=40 .vs 0u
0<=39 .vs 0p
static Args args[] = {
    {XtNheight, (XtArgVal) 100},
    {XtNwidth, (XtArgVal) 200},
XtSetValues(Widget, args, XtNumber(args));

Note that you should not use auto-increment or auto-decrement within the first argument to XtSetArg. XtSetArg can be implemented as a macro that dereferences the first argument twice.

The XtMergeArgLists function allocates enough storage to hold the combined ArgList structures and copies them into it. Note that it does not check for duplicate entries. When it is no longer needed, free the returned storage by using XtFree.

See Also

X Toolkit Intrinsics - C Language Interface
Xlib - C Language X Interface

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