6.7 Structures

6.7.1 newstruct

newstruct(name)

:: Creates a new structure object whose name is name.

return

structure

name

string

• This function creates an new structure object whose name is name.
• A structure named name should be defined in advance.
• Each member of a structure is specified by its name using the operator ->. If the specified member is also an structure, the specification by -> can be nested.

[0] struct list {h,t};    
0
[1] A=newstruct(list);
{0,0}
[2] A->t = newstruct(list);
{0,0}
[3] A; 
{0,{0,0}}
[4] A->h = 1;
1
[5] A->t->h = 2;
2
[6] A->t->t = 3;
3
[7] A;
{1,{2,3}}

References

arfreg, structure definition

6.7.2 arfreg

arfreg(name,add,sub,mul,div,pwr,chsgn,comp)

:: Registers a set of fundamental operations for a type of structure.

return

1

name

string

add sub mul div pwr chsgn comp

user defined functions

• This function registers a set of fundamental operations for a type of structure whose name is name.
• The specification of each function is as follows.

  add(A,B)

  A+B

  sub(A,B)

  A-B

  mul(A,B)

  A*B

  div(A,B)

  A/B

  pwr(A,B)

  A^B

  chsgn(A)

  -A

  comp(A,B)

  1,0,-1 according to the result of a comparison between A and B.

% cat test
struct a {id,body}$

def add(A,B)
{
  C = newstruct(a);
  C->id = A->id; C->body = A->body+B->body;
  return C;
}

def sub(A,B)
{
  C = newstruct(a);
  C->id = A->id; C->body = A->body-B->body;
  return C;
}

def mul(A,B)
{
  C = newstruct(a);
  C->id = A->id; C->body = A->body*B->body;
  return C;
}

def div(A,B)
{
  C = newstruct(a);
  C->id = A->id; C->body = A->body/B->body;
  return C;
}

def pwr(A,B)
{
  C = newstruct(a);
  C->id = A->id; C->body = A->body^B;
  return C;
}

def chsgn(A)
{
  C = newstruct(a);
  C->id = A->id; C->body = -A->body;
  return C;
}

def comp(A,B)
{
  if ( A->body > B->body )
    return 1;
  else if ( A->body < B->body )
    return -1;
  else
    return 0;
}

arfreg("a",add,sub,mul,div,pwr,chsgn,comp)$
end$
% asir
This is Risa/Asir, Version 20000908.
Copyright (C) FUJITSU LABORATORIES LIMITED.
1994-2000. All rights reserved.
[0] load("./test")$
[11] A=newstruct(a);
{0,0}
[12] B=newstruct(a);
{0,0}
[13] A->body = 3;
3
[14] B->body = 4;
4
[15] A*B;
{0,12}

References

newstruct, structure definition

6.7.3 struct_type

struct_type(name|object)

:: Get an identity number of the structure of object and name.

return

an integer

name

string

object

a structure

• struct_type() returns an identity number of the structure or -1 (if an error occurs).

[10] struct list {h,t};    
0
[11] A=newstruct(list);
{0,0}
[12] struct_type(A);
3
[13] struct_type("list");
3

References

newstruct, structure definition

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