fcpp_string is a fortran wrapper for c++ strings designed to (hopefully) make it a bit easier to mix c++ and fortran code. It provides a string type string_t and some basic string formatting string_fmt based on fmtlib.

The string_t type is mostly a straight wrapper of C++'s std::string class. It provides many of the same methods as std::string and for the most part they work in the same way. There are a couple of exceptions such as replace which is implement to operate like Python's replace.

Some simple examples:

type(string_t)            :: s
integer                   :: n
character(:), allocatable :: c

! constructor
s = string_t('a string')

! construct from character
s = 'another fine string'

! replace method
call s % replace('fine', 'simple')

! get string length with size
n = s % size()

! can also use len to get string length
n = len(s)

! find a word
n = s % find('fine')

! concatenation
s = s // ' blah, blah, blah'

! formating integers
s = string_fmt('{06d}', 12) 

! formating floats
s = 'the velocity = ' // string_fmt('{1.2f}', 1.0/3.0) // ' (m/s)' 

! works with print/write 
print *, s

! convert to character with to_character
c = s % to_character()

! or with char
c = char(s)

List of methods available for string_t:

• append
• assignment(=)
• at
• clear
• compare
• copy
• empty
• erase
• find
• initialized
• insert
• operator(+)
• operator(//)
• operator(==)
• operator(/=)
• pop_back
• push_back
• replace
• rfind
• set
• size
• to_character
• write(formatted)

List of helper functions:

• char
• len
• string_fmt