String Manipulation

All methods are type-bound procedures on the string type. Unless stated otherwise they return a new string (or standard character via //'') and do not modify the receiver.

use stringifor
type(string) :: s

Case Conversion

s = 'Hello World'

print "(A)", s%upper()//''      ! HELLO WORLD
print "(A)", s%lower()//''      ! hello world
print "(A)", s%swapcase()//''   ! hELLO wORLD
print "(A)", s%capitalize()//'' ! Hello world  (first char up, rest down)

Word-level case styles

s = ' a StraNgE caSe var'

print "(A)", s%camelcase()//''  !  AStrangeCaseVar
print "(A)", s%snakecase()//''  !  a_strange_case_var
print "(A)", s%startcase()//''  !  A Strange Case Var

Searching and Testing

s = 'Hello World'

print "(L1)", s%start_with('Hello')   ! T
print "(L1)", s%end_with('World')     ! T
print "(L1)", s%is_lower()            ! F
print "(L1)", s%is_upper()            ! F
print "(L1)", s%is_digit()            ! F

! count occurrences of a substring
print "(I0)", s%count('l')            ! 3

Replacing and Modifying

s = 'Hello World'
print "(A)", s%replace(old='World', new='People')//''  ! Hello People

Reverse

s = '0123456789'
print "(A)", s%reverse()//''   ! 9876543210

Unique — collapse repeated substrings

s = 'aabbcc  hello   world'
print "(A)", s%unique(substring=' ')//''  ! aabbcc hello world

Fill / pad

s = '42'
print "(A)", s%fill(width=6)//''             ! 000042  (left-pad with zeros)
print "(A)", s%fill(width=6, right=.true.)//'' ! 420000
print "(A)", s%fill(width=6, fill_char='*')//'' ! ****42

Insert

s = 'Helo'
print "(A)", s%insert(substring='l', pos=3)//''  ! Hello

Strip (trim leading/trailing characters)

s = '   hello   '
print "(A)", s%strip()//''                   ! hello
print "(A)", s%strip(remove=' h')//''        ! ello

Escape / Unescape

s = 'path\to\file'
print "(A)", s%escape()//''    ! path\\to\\file
print "(A)", s%unescape()//''  ! path\to\file

Encode / Decode (Base64)

s = 'Hello World'
print "(A)", s%encode()//''   ! SGVsbG8gV29ybGQ=
print "(A)", s%decode()//''   ! (decodes a Base64 string)

Splitting and Joining

Split

type(string), allocatable :: tokens(:)

s = 'one two three'
call s%split(tokens=tokens, sep=' ')
! tokens(1)='one', tokens(2)='two', tokens(3)='three'

Partition — split at the first occurrence of a separator

type(string) :: parts(3)

s = 'Hello World'
parts = s%partition(sep='lo Wo')
! parts(1) = 'Hel'   (before sep)
! parts(2) = 'lo Wo' (the sep itself)
! parts(3) = 'rld'   (after sep)

Join

type(string) :: words(3)

words(1) = 'one'
words(2) = 'two'
words(3) = 'three'

! join using the receiver as separator
s = '-'
print "(A)", s%join(words)//''          ! one-two-three

! join with an explicit sep argument
print "(A)", s%join(words, sep=', ')//'' ! one, two, three

Slicing

s = 'Hello World'
print "(A)", s%slice(first=1, last=5)//''  ! Hello
print "(A)", s%slice(first=7)//''          ! World

Searching Tagged Records

Useful for extracting content between markup-style delimiters:

s = '<test> <first> hello </first> <first> not first </first> </test>'
print "(A)", s%search(tag_start='<first>', tag_end='</first>')//''
! <first> hello </first>

Temporary Names

type(string) :: tmp

tmp = s%tempname(prefix='my_prefix_')
! returns a unique safe name for a temporary file or directory

Operators

Operator	Result type	Description
//	character	Concatenation; enables seamless use with Fortran intrinsics
.cat.	string	Concatenation returning a string
==, /=	logical	Equality / inequality
<, <=, >=, >	logical	Lexicographic comparison
assignment(=)	—	Assign from character, string, or any PENF numeric kind

Fortran Built-in Replacements

These generic interfaces accept string arguments in place of standard character:

adjustl, adjustr, count, index, len_trim, repeat, scan, trim, verify

type(string) :: s
s = '  hello  '
print "(A)", trim(s)//''         ! hello
print "(I0)", len_trim(s)        ! 5
print "(I0)", index(s, 'ell')    ! 3