.. index:: single: string(Representation) .. _string/1:

.. rst-class:: right

object

`string(Representation)`

Representation - String representation. Valid values are atom, codes, and chars. String manipulation predicates supporting different string representations.
| Availability: | logtalk_load(strings(loader))

| Author: Paulo Moura | Version: 1:0:0 | Date: 2026-02-03

| Compilation flags: | static, context_switching_calls

| Uses: | :ref:`list <list/0>`

| Remarks: | (none)

| Inherited public predicates: | (none)

.. contents:: :local: :backlinks: top

Public predicates

.. index:: atom_string/2 .. _string/1::atom_string/2:

atom_string/2 ^^^^^^^^^^^^^^^^^

Converts between an atom and a string.

| Compilation flags: | static

.. index:: number_string/2 .. _string/1::number_string/2:

number_string/2 ^^^^^^^^^^^^^^^^^^^

Converts between a number and a string. Fails if the string does not represent a valid number.

| Compilation flags: | static

.. index:: string_chars/2 .. _string/1::string_chars/2:

string_chars/2 ^^^^^^^^^^^^^^^^^^

Converts between a string and a list of characters.

| Compilation flags: | static

.. index:: string_codes/2 .. _string/1::string_codes/2:

string_codes/2 ^^^^^^^^^^^^^^^^^^

Converts between a string and a list of character codes.

| Compilation flags: | static

.. index:: string_concat/3 .. _string/1::string_concat/3:

string_concat/3 ^^^^^^^^^^^^^^^^^^^

Concatenates two strings.

| Compilation flags: | static

.. index:: string_length/2 .. _string/1::string_length/2:

string_length/2 ^^^^^^^^^^^^^^^^^^^

Returns the length of a string.

| Compilation flags: | static

| Template: | string_length(String,Length) | Mode and number of proofs: | string_length(+text,?integer) - zero_or_one

.. index:: sub_string/5 .. _string/1::sub_string/5:

sub_string/5 ^^^^^^^^^^^^^^^^

Extracts a substring from a string.

| Compilation flags: | static

| Template: | sub_string(String,Before,Length,After,SubString) | Mode and number of proofs: | sub_string(+text,?integer,?integer,?integer,?text) - zero_or_more

.. index:: string_upper/2 .. _string/1::string_upper/2:

string_upper/2 ^^^^^^^^^^^^^^^^^^

Converts a string to uppercase (ASCII only).

| Compilation flags: | static

| Template: | string_upper(String,UpperString) | Mode and number of proofs: | string_upper(+text,?text) - zero_or_one

.. index:: string_lower/2 .. _string/1::string_lower/2:

string_lower/2 ^^^^^^^^^^^^^^^^^^

Converts a string to lowercase (ASCII only).

| Compilation flags: | static

| Template: | string_lower(String,LowerString) | Mode and number of proofs: | string_lower(+text,?text) - zero_or_one

.. index:: split_string/4 .. _string/1::split_string/4:

split_string/4 ^^^^^^^^^^^^^^^^^^

Decomposes String into SubStrings according to separators SepChars and padding characters PadChars. The string is split at the separators, and any padding characters around the resulting sub-strings are removed. Characters in both SepChars and PadChars are treated as separators where sequences count as one separator, and are ignored at string boundaries.

| Compilation flags: | static

| Template: | split_string(String,SepChars,PadChars,SubStrings) | Mode and number of proofs: | split_string(+text,+text,+text,-list(text)) - one

.. index:: atomics_to_string/2 .. _string/1::atomics_to_string/2:

atomics_to_string/2 ^^^^^^^^^^^^^^^^^^^^^^^

Concatenates the atomic terms in List into String. The list may contain numbers, atoms, and strings (in the current representation).

| Compilation flags: | static

| Template: | atomics_to_string(List,String) | Mode and number of proofs: | atomics_to_string(++list(atomic),-text) - one

.. index:: atomics_to_string/3 .. _string/1::atomics_to_string/3:

atomics_to_string/3 ^^^^^^^^^^^^^^^^^^^^^^^

Concatenates the atomic terms in List into String, with Separator inserted between each element. The list may contain numbers, atoms, and strings (in the current representation).

| Compilation flags: | static

| Template: | atomics_to_string(List,Separator,String) | Mode and number of proofs: | atomics_to_string(++list(atomic),+text,-text) - one

.. index:: trim/2 .. _string/1::trim/2:

trim/2 ^^^^^^^^^^

Trims string by deleting all leading and trailing whitespace.

| Compilation flags: | static

| Template: | trim(String,Trimmed) | Mode and number of proofs: | trim(+text,-text) - one

.. index:: trim/3 .. _string/1::trim/3:

trim/3 ^^^^^^^^^^

Trims string by deleting all occurrences of the characters in Elements from the beginning and end of the string.

| Compilation flags: | static

| Template: | trim(String,Elements,Trimmed) | Mode and number of proofs: | trim(+text,+text,-text) - one

.. index:: trim_left/2 .. _string/1::trim_left/2:

trim_left/2 ^^^^^^^^^^^^^^^

Trims string by deleting all leading whitespace.

| Compilation flags: | static

| Template: | trim_left(String,Trimmed) | Mode and number of proofs: | trim_left(+text,-text) - one

.. index:: trim_left/3 .. _string/1::trim_left/3:

trim_left/3 ^^^^^^^^^^^^^^^

Trims string by deleting all occurrences of the characters in Elements from the beginning of the string.

| Compilation flags: | static

| Template: | trim_left(String,Elements,Trimmed) | Mode and number of proofs: | trim_left(+text,+text,-text) - one

.. index:: trim_right/2 .. _string/1::trim_right/2:

trim_right/2 ^^^^^^^^^^^^^^^^

Trims string by deleting all trailing whitespace.

| Compilation flags: | static

| Template: | trim_right(String,Trimmed) | Mode and number of proofs: | trim_right(+text,-text) - one

.. index:: trim_right/3 .. _string/1::trim_right/3:

trim_right/3 ^^^^^^^^^^^^^^^^

Trims string by deleting all occurrences of the characters in Elements from the end of the string.

| Compilation flags: | static

| Template: | trim_right(String,Elements,Trimmed) | Mode and number of proofs: | trim_right(+text,+text,-text) - one

Protected predicates

(no local declarations; see entity ancestors if any)

Private predicates

(no local declarations; see entity ancestors if any)

Operators

(none)