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Size: 524
Comment: first-line; also a bit more explicit wording
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Size: 1014
Comment: Mark which version works where; add awk version; cosmetics
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| The fastest way, not requiring external programs (but usable only with [[BASH]] and KornShell): | The fastest way, not requiring external programs (but not usable in Bourne shells): |
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| # POSIX | |
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| # Bourne | |
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| Another one: | or: |
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| # Bourne, with GNU expr(1) | |
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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 {{{$varname}}} expands to {{{"length"}}}, the first version will fail with BSD/GNU {{{expr}}}. One may also use `awk`: {{{ # Bourne awk -v x="$varname" 'BEGIN {print length(x)}' }}} ------ Similar needs: {{{ # Korn/Bash ${#arrayname[@]} }}} Returns the number of elements in an array. {{{ # Korn/Bash ${#arrayname[i]} }}} Returns the length of the array's element i. ---- CategoryShell |
Is there a function to return the length of a string?
The fastest way, not requiring external programs (but not usable in Bourne shells):
# POSIX
${#varname}or for Bourne shells:
# Bourne expr "$varname" : '.*'
(expr prints the number of characters matching the pattern .*, which is the length of the string.)
or:
# Bourne, with GNU expr(1) expr length "$varname"
(BSD/GNU expr only)
This second version is not specified in POSIX, so is not portable across all platforms. However, if $varname expands to "length", the first version will fail with BSD/GNU expr.
One may also use awk:
# Bourne
awk -v x="$varname" 'BEGIN {print length(x)}'
Similar needs:
# Korn/Bash
${#arrayname[@]}Returns the number of elements in an array.
# Korn/Bash
${#arrayname[i]}Returns the length of the array's element i.