---
name: "XtSetArg"
section: "3x"
platform: "linux"
package: "libxt-dev"
version: "4.3.0.dfsg.1-14sarge7"
release: "Debian 3.1 (Sarge)"
platforms: ["linux"]
url: "https://new.carta.tech/XtSetArg/3x"
---

# XtSetArg(3x)

set and merge ArgLists

## NAME

XtSetArg, XtMergeArgLists - set and merge ArgLists

## SYNTAX

int XtSetArg(Arg *arg*, String *name*, XtArgVal *value*);

ArgList XtMergeArgLists(ArgList *args1*, Cardinal *num\_args1*, ArgList *args2*, Cardinal *num\_args2*);

## ARGUMENTS

- *arg*

  Specifies the name-value pair to set.

- *args1*

  Specifies the first *ArgList*.

- *args2*

  Specifies the second  *ArgList*.

- *num\_args1*

  Specifies the number of arguments in the first argument list.

- *num\_args2*

  Specifies the number of arguments in the second argument list.

- *name*

  Specifies the name of the resource.

- *value*

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

## DESCRIPTION

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

```
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*:

```
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

XtOffset(3Xt)\
 *X Toolkit Intrinsics - C Language Interface*\
 *Xlib - C Language X Interface*