The IsPrefix( s, t ) command determines whether s is a prefix (initial substring) of t.

The string s is a prefix of the string t if $\mathrm{s1}=t_{1..n}$, for some integer $1\le n$, or s is the empty string.

If s is a prefix of t, IsPrefix returns true. Otherwise, false is returned.

Note: The IsPrefix( s, t ) command is equivalent to the expression

The IsSuffix( s, t ) command determines whether s is a suffix (terminal substring) of t.

If s is a suffix of t, IsSuffix returns true. Otherwise, false is returned.

Note: The IsSuffix( s, t ) command is equivalent to the expression

All of the StringTools package commands treat strings as (null-terminated) sequences of $8$-bit (ASCII) characters.  Thus, there is no support for multibyte character encodings, such as unicode encodings.

The StringTools[IsPrefix] and StringTools[IsSuffix] commands are thread-safe as of Maple 15.

For more information on thread safety, see index/threadsafe.

$\mathrm{with}\left(\mathrm{StringTools}\right)\:$

$\mathrm{IsPrefix}\left(''''\,''abc''\right)$

$\mathrm{true}$

$\mathrm{IsPrefix}\left(''a''\,''abc''\right)$

$\mathrm{true}$

$\mathrm{IsPrefix}\left(''ab''\,''abc''\right)$

$\mathrm{true}$

$\mathrm{IsPrefix}\left(''abc''\,''abc''\right)$

$\mathrm{true}$

$\mathrm{IsPrefix}\left(''abcd''\,''abc''\right)$

$\mathrm{false}$

$\mathrm{IsPrefix}\left(''ac''\,''abc''\right)$

$\mathrm{false}$

$\mathrm{IsSuffix}\left(''''\,''abc''\right)$

$\mathrm{true}$

$\mathrm{IsSuffix}\left(''c''\,''abc''\right)$

$\mathrm{true}$

$\mathrm{IsSuffix}\left(''bc''\,''abc''\right)$

$\mathrm{true}$

$\mathrm{IsSuffix}\left(''abc''\,''abc''\right)$

$\mathrm{true}$

$\mathrm{IsSuffix}\left(''xabc''\,''abc''\right)$

$\mathrm{false}$

$\mathrm{IsPrefix}\left(''foo''\,''foobar''\right)$

$\mathrm{true}$

$S≔\left[\mathrm{seq}\right]\left(''foobar''\left[1..i\right]\,i=0..\mathrm{length}\left(''foobar''\right)\right)$

$S≔\left[''''\,''f''\,''fo''\,''foo''\,''foob''\,''fooba''\,''foobar''\right]$

$\mathrm{member}\left(''foo''\,S\right)$

$\mathrm{true}$

$s≔\mathrm{Random}\left(100\right)\:$

$\mathrm{length}\left(s\right)$

$100$

$\left\{\mathrm{seq}\left(\mathrm{IsSuffix}\left(\mathrm{Drop}\left(s\,i\right)\,s\right)\,i=1..\mathrm{length}\left(s\right)\right)\right\}$

$\left\{\mathrm{true}\right\}$

$\left\{\mathrm{seq}\left(\mathrm{IsPrefix}\left(\mathrm{Take}\left(s\,i\right)\,s\right)\,i=1..\mathrm{length}\left(s\right)\right)\right\}$

$\left\{\mathrm{true}\right\}$