### Home Classes Methods

### In Files

- lib/ffi/pointer.rb

### Parent

Object

### Methods

- ::size
- #read_array_of_type
- #read_string
- #read_string_length
- #read_string_to_null
- #write_array_of_type
- #write_string
- #write_string_length

### Files

- History.txt
- README.rdoc

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# FFI::Pointer

### Constants

SIZE

  Pointer size

### Public Class Methods

size() click to toggle source

Return the size of a pointer on the current platform, in bytes @return [Numeric]

    # File lib/ffi/pointer.rb, line 30
    def self.size
      SIZE
    end

### Public Instance Methods

read_array_of_type(type, reader, length) click to toggle source

@param [Type] type type of data to read from pointer’s contents @param [Symbol] reader method to send to `self` to read `type` @param [Numeric] length @return [Array] Read an array of `type` of length `length`. @example

    ptr.write_array_of_type(TYPE_UINT8, :get_uint8, 4) # -> [1, 2, 3, 4]

    # File lib/ffi/pointer.rb, line 94
    def read_array_of_type(type, reader, length)
      ary = []
      size = FFI.type_size(type)
      tmp = self
      length.times { |j|
        ary << tmp.send(reader)
        tmp += size unless j == length-1 # avoid OOB
      }
      ary
    end

read_string(len=nil) click to toggle source

@param [nil,Numeric] len length of string to return @return [String] Read pointer’s contents as a string, or the first `len` bytes of the equivalent string if `len` is not `nil`.

    # File lib/ffi/pointer.rb, line 38
    def read_string(len=nil)
      if len
        get_bytes(0, len)
      else
        get_string(0)
      end
    end

read_string_length(len) click to toggle source

@param [Numeric] len length of string to return @return [String] Read the first `len` bytes of pointer’s contents as a string.

Same as:

    ptr.read_string(len)  # with len not nil

    # File lib/ffi/pointer.rb, line 52
    def read_string_length(len)
      get_bytes(0, len)
    end

read_string_to_null() click to toggle source

@return [String] Read pointer’s contents as a string.

Same as:

    ptr.read_string  # with no len

    # File lib/ffi/pointer.rb, line 61
    def read_string_to_null
      get_string(0)
    end

write_array_of_type(type, writer, ary) click to toggle source

@param [Type] type type of data to write to pointer’s contents @param [Symbol] writer method to send to `self` to write `type` @param [Array] ary @return [self] Write `ary` in pointer’s contents as `type`. @example

    ptr.write_array_of_type(TYPE_UINT8, :put_uint8, [1, 2, 3 ,4])

    # File lib/ffi/pointer.rb, line 112
    def write_array_of_type(type, writer, ary)
      size = FFI.type_size(type)
      tmp = self
      ary.each_with_index {|i, j|
        tmp.send(writer, i)
        tmp += size unless j == ary.length-1 # avoid OOB
      }
      self
    end

write_string(str, len=nil) click to toggle source

@param [String] str string to write @param [Numeric] len length of string to return @return [self] Write `str` in pointer’s contents, or first `len` bytes if `len` is not `nil`.

    # File lib/ffi/pointer.rb, line 81
    def write_string(str, len=nil)
      len = str.bytesize unless len
      # Write the string data without NUL termination
      put_bytes(0, str, 0, len)
    end

write_string_length(str, len) click to toggle source

@param [String] str string to write @param [Numeric] len length of string to return @return [self] Write `len` first bytes of `str` in pointer’s contents.

Same as:

    ptr.write_string(str, len)   # with len not nil

    # File lib/ffi/pointer.rb, line 72
    def write_string_length(str, len)
      put_bytes(0, str, 0, len)
    end

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