### 5.1.165 write

`Syntax:`
  `write (` link_expression`,` expression_list `)`
  for DBM links:
  `write (` link`,` string_expression`,` string_expression `)`
  `write (` link`,` string_expression `)`
`Type:`
  none
`Purpose:`
  writes data to a link.
  If the link is of type `ASCII`, all expressions are converted to strings (and separated by a newline character) before they are written. As a consequence, only such values which can be converted to a string can be written to an `ASCII` link.
  For ssi links, ring-dependent expressions are written together with a ring description. To prevent an evaluation of the expression before it is written, the `quote` command (possibly together with `eval`) can be used. A `write` blocks (i.e., does not return to the prompt), as long as a ssi link is not ready for writing.
  For DBM links, `write` with three arguments inserts the first string as key and the second string as value into the dbm data base.
  Called with two arguments, it deletes the entry with the key specified by the string from the data base.
`Example:`

      // write the values of the variables f and i as strings into
      // the file "outfile" (overwrite it, if it exists)
      write(":w outfile",f,i);

      // now append the string "that was f,i" (without the quotes)
      // at the end of the file "outfile"
      write(":a outfile","that was f,i");
      // alternatively, links could be used:
      link l=":a outfile"; l;
      // type : ASCII
      // mode : a
      // name : outfile
      // open : no
      // read : not ready
      // write: not ready
      write(l," that was f,i");
      // saving and retrieving data (ASCII format):
      ring r=32003,(x,y,z),dp;
      ideal i=x+y,z3+22y;
      write(":w save_i",i);// this writes x+y,z3+22y to the file save_i
      ring r=32003,(x,y,z),dp;
      string s=read("save_i");   //creates the string x+y,z3+22y
      execute("ideal k="+s+";"); // this defines an ideal k which
                                 // is equal to i.
      // for large objects, the ssi format and ssi links are better:
      write("ssi:w save_i.ssi",i);
      def j=read("ssi:r save_i.ssi");

See Data types; dump; eval; link; print; printf; quote; read; short.

User manual for Singular version 4-0-3, 2016, generated by texi2html.