/tutorial/external/C/example1.e

  1class EXAMPLE1
  2   --
  3   -- How to use external "C" features (i.e. calling C from Eiffel).
  4   --
  5   -- To compile this file:
  6   --
  7   --       compile example1 c_glue1.c
  8   --
  9   -- You may also prefer:
 10   --
 11   --       gcc -c c_glue1.c
 12   --       compile example1 c_glue1.o
 13   --
 14
 15inherit
 16   ANY
 17
 18create {ANY}
 19   make
 20
 21feature {ANY}
 22   make
 23      local
 24         i: INTEGER; c: CHARACTER
 25      do
 26         -- To send an INTEGER to the C world:
 27         integer_to_c(6)
 28         -- To send a CHARACTER to the C world:
 29         character_to_c('a')
 30         -- To send a BOOLEAN to the C world:
 31         boolean_to_c(True)
 32         -- To send a REAL (i.e. a REAL_64) to the C world:
 33         real_64_to_c(3.5)
 34         -- To send a REAL_32 to the C world:
 35         real_32_to_c({REAL_32 3.5})
 36         -- To send the internal storage of a STRING to the C world:
 37         string_storage_to_c(("Hi C World %N").to_external)
 38         -- To send `Current' address to the C world:
 39         any_to_c(Current)
 40         -- To send a STRING to the C world:
 41         any_to_c(create {ANY_STRING}.make_from_string("Hi"))
 42         -- To get an INTEGER from the C world:
 43         i := c_int2eiffel
 44         io.put_integer(i)
 45         -- To get an CHARACTER from the C world:
 46         c := c_char2eiffel
 47         io.put_character(c)
 48         -- To pass the address on an INTEGER attribute:
 49         set_integer_attribute($integer_attribute)
 50         std_output.put_integer(integer_attribute)
 51         std_output.put_new_line
 52         -- Calling the hello C function:
 53         if hello then
 54            std_output.put_string(" C man !%N")
 55         end
 56      end
 57
 58feature {}
 59   integer_to_c (i: INTEGER)
 60         -- Call the C `integer_to_c' function with `i' as argument (see c_glue1.c).
 61      external "C"
 62      end
 63
 64   character_to_c (c: CHARACTER)
 65         -- Call the C `character_to_c' function with `c' as argument (see c_glue1.c).
 66      external "C"
 67      end
 68
 69   boolean_to_c (b: BOOLEAN)
 70         -- Call the C `boolean_to_c' function with `b' as argument (see c_glue1.c).
 71      external "C"
 72      end
 73
 74   real_32_to_c (r: REAL_32)
 75         -- Call the C `real_32_to_c' function with `r' as argument (see c_glue1.c).
 76      external "C"
 77      end
 78
 79   real_64_to_c (d: REAL_64)
 80         -- Call the C `real_64_to_c' function with `d' as argument (see c_glue1.c).
 81      external "C"
 82      end
 83
 84   string_storage_to_c (s: POINTER)
 85         -- Call the C `string_storage_to_c' function with `s' as argument (see
 86         -- c_glue1.c).
 87      external "C"
 88      end
 89
 90   any_to_c (a: ANY)
 91         -- Call the C `any_to_c' function with `a' as argument (see c_glue1.c).
 92      external "C"
 93      end
 94
 95   c_int2eiffel: INTEGER
 96         -- Call the C `c_int2eiffel' function (see c_glue1.c).
 97      external "C"
 98      end
 99
100   c_char2eiffel: CHARACTER
101         -- Call the C `c_char2eiffel' function (see c_glue1.c).
102      external "C"
103      end
104
105   integer_attribute: INTEGER
106
107   set_integer_attribute (integer_pointer: POINTER)
108         -- Call the C `set_integer_attribute' function with the address of an
109         -- INTEGER attribute (see c_glue1.c).
110      external "C"
111      end
112
113   hello: BOOLEAN
114      external "C"
115      end
116
117end -- class EXAMPLE1