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base-4.14.1.0: Basic libraries
Copyright(c) The FFI task force 2001
LicenseBSD-style (see the file libraries/base/LICENSE)
Maintainerffi@haskell.org
Stabilityprovisional
Portabilityportable
Safe HaskellTrustworthy
LanguageHaskell2010

Foreign.C.String

Contents

Description

Utilities for primitive marshalling of C strings.

The marshalling converts each Haskell character, representing a Unicode code point, to one or more bytes in a manner that, by default, is determined by the current locale. As a consequence, no guarantees can be made about the relative length of a Haskell string and its corresponding C string, and therefore all the marshalling routines include memory allocation. The translation between Unicode and the encoding of the current locale may be lossy.

Synopsis

C strings

typeCString =PtrCCharSource#

A C string is a reference to an array of C characters terminated by NUL.

typeCStringLen = (PtrCChar,Int)Source#

A string with explicit length information in bytes instead of a terminating NUL (allowing NUL characters in the middle of the string).

Using a locale-dependent encoding

These functions are different from theirCAString counterparts in that they will use an encoding determined by the current locale, rather than always assuming ASCII.

peekCString ::CString ->IOStringSource#

Marshal a NUL terminated C string into a Haskell string.

peekCStringLen ::CStringLen ->IOStringSource#

Marshal a C string with explicit length into a Haskell string.

newCString ::String ->IOCStringSource#

Marshal a Haskell string into a NUL terminated C string.

  • the Haskell string maynot contain any NUL characters
  • new storage is allocated for the C string and must be explicitly freed usingfree orfinalizerFree.

newCStringLen ::String ->IOCStringLenSource#

Marshal a Haskell string into a C string (ie, character array) with explicit length information.

  • new storage is allocated for the C string and must be explicitly freed usingfree orfinalizerFree.

withCString ::String -> (CString ->IO a) ->IO aSource#

Marshal a Haskell string into a NUL terminated C string using temporary storage.

  • the Haskell string maynot contain any NUL characters
  • the memory is freed when the subcomputation terminates (either normally or via an exception), so the pointer to the temporary storage mustnot be used after this.

withCStringLen ::String -> (CStringLen ->IO a) ->IO aSource#

Marshal a Haskell string into a C string (ie, character array) in temporary storage, with explicit length information.

  • the memory is freed when the subcomputation terminates (either normally or via an exception), so the pointer to the temporary storage mustnot be used after this.

charIsRepresentable ::Char ->IOBoolSource#

Using 8-bit characters

These variants of the above functions are for use with C libraries that are ignorant of Unicode. These functions should be used with care, as a loss of information can occur.

castCharToCChar ::Char ->CCharSource#

Convert a Haskell character to a C character. This function is only safe on the first 256 characters.

castCCharToChar ::CChar ->CharSource#

Convert a C byte, representing a Latin-1 character, to the corresponding Haskell character.

castCharToCUChar ::Char ->CUCharSource#

Convert a Haskell character to a Cunsigned char. This function is only safe on the first 256 characters.

castCUCharToChar ::CUChar ->CharSource#

Convert a Cunsigned char, representing a Latin-1 character, to the corresponding Haskell character.

castCharToCSChar ::Char ->CSCharSource#

Convert a Haskell character to a Csigned char. This function is only safe on the first 256 characters.

castCSCharToChar ::CSChar ->CharSource#

Convert a Csigned char, representing a Latin-1 character, to the corresponding Haskell character.

peekCAString ::CString ->IOStringSource#

Marshal a NUL terminated C string into a Haskell string.

peekCAStringLen ::CStringLen ->IOStringSource#

Marshal a C string with explicit length into a Haskell string.

newCAString ::String ->IOCStringSource#

Marshal a Haskell string into a NUL terminated C string.

  • the Haskell string maynot contain any NUL characters
  • new storage is allocated for the C string and must be explicitly freed usingfree orfinalizerFree.

newCAStringLen ::String ->IOCStringLenSource#

Marshal a Haskell string into a C string (ie, character array) with explicit length information.

  • new storage is allocated for the C string and must be explicitly freed usingfree orfinalizerFree.

withCAString ::String -> (CString ->IO a) ->IO aSource#

Marshal a Haskell string into a NUL terminated C string using temporary storage.

  • the Haskell string maynot contain any NUL characters
  • the memory is freed when the subcomputation terminates (either normally or via an exception), so the pointer to the temporary storage mustnot be used after this.

withCAStringLen ::String -> (CStringLen ->IO a) ->IO aSource#

Marshal a Haskell string into a C string (ie, character array) in temporary storage, with explicit length information.

  • the memory is freed when the subcomputation terminates (either normally or via an exception), so the pointer to the temporary storage mustnot be used after this.

C wide strings

These variants of the above functions are for use with C libraries that encode Unicode using the Cwchar_t type in a system-dependent way. The only encodings supported are

  • UTF-32 (the C compiler defines201706L), or
  • UTF-16 (as used on Windows systems).

typeCWString =PtrCWcharSource#

A C wide string is a reference to an array of C wide characters terminated by NUL.

typeCWStringLen = (PtrCWchar,Int)Source#

A wide character string with explicit length information inCWchars instead of a terminating NUL (allowing NUL characters in the middle of the string).

peekCWString ::CWString ->IOStringSource#

Marshal a NUL terminated C wide string into a Haskell string.

peekCWStringLen ::CWStringLen ->IOStringSource#

Marshal a C wide string with explicit length into a Haskell string.

newCWString ::String ->IOCWStringSource#

Marshal a Haskell string into a NUL terminated C wide string.

  • the Haskell string maynot contain any NUL characters
  • new storage is allocated for the C wide string and must be explicitly freed usingfree orfinalizerFree.

newCWStringLen ::String ->IOCWStringLenSource#

Marshal a Haskell string into a C wide string (ie, wide character array) with explicit length information.

  • new storage is allocated for the C wide string and must be explicitly freed usingfree orfinalizerFree.

withCWString ::String -> (CWString ->IO a) ->IO aSource#

Marshal a Haskell string into a NUL terminated C wide string using temporary storage.

  • the Haskell string maynot contain any NUL characters
  • the memory is freed when the subcomputation terminates (either normally or via an exception), so the pointer to the temporary storage mustnot be used after this.

withCWStringLen ::String -> (CWStringLen ->IO a) ->IO aSource#

Marshal a Haskell string into a C wide string (i.e. wide character array) in temporary storage, with explicit length information.

  • the memory is freed when the subcomputation terminates (either normally or via an exception), so the pointer to the temporary storage mustnot be used after this.

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