Diff for "BashFAQ/007"

Differences between revisions 5 and 6

Is there a function to return the length of a string?

The fastest way, not requiring external programs (but usable only with BASH and KornShell):

${#varname}

or for Bourne shells:

expr "$varname" : '.*'

(expr prints the number of characters matching the pattern .*, which is the length of the string.)

or:

expr length "$varname"

(BSD/GNU expr only)

This second version is not specified in POSIX, so is not portable across all platforms.

However, if $varname expands to "length", the first version will fail with BSD/GNU expr.

${#arrayname[@]}

Returns the Number of Elements in an Array.

${#arrayname[i]}

Returns the length of the Arrays Element i.

-  ⇤ ← Revision 5 as of 2009-12-29 17:23:36 → 
  Size: 701
  Editor: MatthiasPopp
  Comment:
+   ← Revision 6 as of 2011-02-28 22:27:41 → ⇥
  Size: 830
  Editor: 203-214-41-227
  Comment: what if $varname == "length" :-(
-Deletions are marked like this.
+Additions are marked like this.
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-Another one:
+or:
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-(This is for a BSD/GNU version of {{{expr}}}. Do not use this, because it is not [[POSIX]]).
+(BSD/GNU {{{expr}}} only)

This second version is not specified in [[POSIX]], so is not portable across all platforms.

However, if {{{$varname}}} expands to {{{"length"}}}, the first version will fail with BSD/GNU {{{expr}}}.