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

The fastest way, not requiring external programs (but not usable in Bourne shells):


or for Bourne shells:

# Bourne
expr "$varname" : '.*'

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


# 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.

A portable way is:

expr \( "X$varname" : ".*" \) - 1

One may also use awk:

# Bourne
awk -v x="$varname" 'BEGIN {print length(x)}'

Though that one will fail for values of $varname that contain backslash characters, so you may prefer:

# Bourne with POSIX awk
awk  'BEGIN {print length(ARGV[1]);exit}' "$varname"

Similar needs:

# Korn/Bash

Returns the number of elements in an array.

# Korn/Bash

Returns the length of the array's element i.


2012-07-01 04:05