lpop(n) Tcl Built-In Commands lpop(n)

```

```

# [NAME](#NAME)

lpop - Get and remove an element in a list

# [SYNOPSIS](#SYNOPSIS)

**lpop varName** ?*index ...*?

```

```

# [DESCRIPTION](#DESCRIPTION)

The **lpop** command accepts a parameter, *varName*, which it interprets as the name of a variable containing a Tcl list. It also accepts one or more *indices* into the list. If no indices are presented, it defaults to "**end**".

When presented with a single index, the **lpop** command addresses the *index*'th element in it, removes if from the list and returns the element.

If *index* is negative or greater or equal than the number of elements in the list in the variable called *varName*, an error occurs.

The interpretation of each simple *index* value is the same as for the command **string index**, supporting simple index arithmetic and indices relative to the end of the list.

If additional *index* arguments are supplied, then each argument is used in turn to address an element within a sublist designated by the previous indexing operation, allowing the script to remove elements in sublists, similar to **lindex** and **lset**. The command,

```
lpop a 1 2
```

gets and removes element 2 of sublist 1.

# [EXAMPLES](#EXAMPLES)

In each of these examples, the initial value of *x* is:

```
set x [list [list a b c] [list d e f] [list g h i]]


      → {a b c} {d e f} {g h i}
```

The indicated value becomes the new value of *x* (except in the last case, which is an error which leaves the value of *x* unchanged.)

```
lpop x 0


      → {d e f} {g h i}
lpop x 2


      → {a b c} {d e f}
lpop x end


      → {a b c} {d e f}
lpop x end-1


      → {a b c} {g h i}
lpop x 2 1


      → {a b c} {d e f} {g i}
lpop x 2 3 j


      → list index out of range
```

In the following examples, the initial value of *x* is:

```
set x [list [list [list a b] [list c d]] \


            [list [list e f] [list g h]]]


      → {{a b} {c d}} {{e f} {g h}}
```

The indicated value becomes the new value of *x*.

```
lpop x 1 1 0


      → {{a b} {c d}} {{e f} h}
```

# [SEE ALSO](#SEE_ALSO)

[list(n)](/man/os/tcl/list.n), [lappend(n)](/man/os/tcl/lappend.n), [lassign(n)](/man/os/tcl/lassign.n), [ledit(n)](/man/os/tcl/ledit.n), [lindex(n)](/man/os/tcl/lindex.n), [linsert(n)](/man/os/tcl/linsert.n), [llength(n)](/man/os/tcl/llength.n), [lmap(n)](/man/os/tcl/lmap.n), [lrange(n)](/man/os/tcl/lrange.n), [lremove(n)](/man/os/tcl/lremove.n), [lrepeat(n)](/man/os/tcl/lrepeat.n), [lreplace(n)](/man/os/tcl/lreplace.n), [lreverse(n)](/man/os/tcl/lreverse.n), [lsearch(n)](/man/os/tcl/lsearch.n), [lseq(n)](/man/os/tcl/lseq.n), [lset(n)](/man/os/tcl/lset.n), [lsort(n)](/man/os/tcl/lsort.n), [string(n)](/man/os/tcl/string.n)

# [KEYWORDS](#KEYWORDS)

element, index, list, remove, pop, stack, queue

9.0 Tcl

---

Document: lpop(n) from tcl 9.1.0-r1 (Chainguard OS)
Source: https://downloads.sourceforge.net/project/tcl/Tcl/9.1.0/tcl9.1.0-src.tar.gz