Editing Module:String/doc (section)

== find ==

This function allows one to search for a target string or pattern within another string.

Usage:

: <code><nowiki>{{#invoke:</nowiki>String|find|''source_string''|''target_string''|''start_index''|''plain_flag''}}</code>

OR

: <code><nowiki>{{#invoke:</nowiki>String|find|source= ''source_string'' |target= ''target_string'' |start= ''start_index'' |plain= ''plain_flag'' }}</code>

Parameters:

; source
: The string to search
; target
: The string or pattern to find within source
; start
: The index within the source string to start the search, defaults to 1
; plain
: Boolean flag indicating that target should be understood as plain text and not as a [[mw:Extension:Scribunto/Lua reference manual#Ustring patterns|Scribunto ustring pattern]] (a unicode-friendly [[w:Lua (programming language)|Lua]]-style [[w:regular expression|regular expression]]); defaults to true

This function returns the first index >= "start" where "target" can be found within "source". Indices are 1-based. If "target" is not found, then this function returns 0. If either "source" or "target" are missing / empty, this function also returns 0.

This function should be safe for UTF-8 strings.

Examples:
* <code><nowiki>{{#invoke:String|find|abc123def|12}}</nowiki></code> → {{#invoke:String|find|abc123def|12}}
* <code><nowiki>{{#invoke:String|find|source=abc123def|target=12}}</nowiki></code> → {{#invoke:String|find|source=abc123def|target=12}}
* <code><nowiki>{{#invoke:String|find|source=abc123def|target=pqr}}</nowiki></code> → {{#invoke:String|find|source=abc123def|target=pqr}}
* <code><nowiki>{{#invoke:String|find| abc123def |123}}</nowiki></code> → {{#invoke:String|find| abc123def |123}}
* <code><nowiki>{{#invoke:String|find|source= abc123def |target= 123 }}</nowiki></code> → {{#invoke:String|find|source= abc123def |target= 123 }}
* <code><nowiki>{{#invoke:String|find|source=abc123def|target=%d |start=3 |plain=false }}</nowiki></code> → {{#invoke:String|find|source=abc123def|target=%d |start=3 |plain=false }}

When using unnamed parameters, preceding and trailing spaces are kept and counted:
* <code><nowiki>{{#invoke:String|find|  abc123def |c|false}}</nowiki></code> → {{#invoke:String|find|  abc123def |c|false}}
* <code><nowiki>{{#invoke:String|find|source=  abc123def |target=c|plain=false}}</nowiki></code> → {{#invoke:String|find|source=  abc123def |target=c|plain=false}}
* <code><nowiki>{{#invoke:string|find|abc 123 def|%s|plain=false}}</nowiki></code> → {{#invoke:string|find|abc 123 def|%s|plain=false}}

Testing for the presence of a string:
* <code>{{pf|ifexpr|<nowiki>{{#invoke:string|find|haystack|needle}}</nowiki>|Found needle|Didn't find needle}}</code> → {{#ifexpr:{{#invoke:string|find|haystack|needle}}|Found needle|Didn't find needle}}

{{anchor|replace}}