h.dowhile

来自「强大的数学工具包」· DOWHILE 代码 · 共 53 行

                               * * * * * * *
                               *  dowhile  *
                               * * * * * * *

        "dowhile-loop"
        SYNTAX: dowhile(B, seq)


        B is a boolean expression. seq is executed as long as the
        value of B is nonzero, but at least once.

        seq is a sequence of several expressions, separated by '_' or 
        ';'. If an expression ends with '_', its output is displayed,
        if it ends with ';', its output is suppressed. The sequence
        must not be empty.
        Remark: The last expression of seq must not be terminated by 
                '_' and need not be terminated by ';'. If you want its 
                output to be suppressed, terminate it by ';'.
                To avoid the output of unnecessary results during the 
                computation, please use ';'.
        At the end of the outermost loop, the values of all variables 
        used during the computation are displayed.

        Endless loops are not recognized. Type "CTRL/C" to interrupt 
        the loop. In that case, the value of all variables are 
        displayed.

        The overwrite protection mechanism is automatically disabled
        in a loop. At the end of the loop, it is restored.
  
        If an error occurs, the user is asked, if the loop should be
        continued. If the answer is positive, the actual loop is continued, 
        else the loop is left.

        "break" and "continue" may be used (see "? break","? continue").


        Example 1: (correct)

                dowhile(a > 0, fact(a)_a=a-1;)


        Example 2: (correct)

                dowhile(a>=(-5), if(a>=0,b=sqrt(a),break)_a=a-1;)


        Example 3: (incorrect)

                dowhile( t>2, r=3, t=t-1 )

_ERR_NR_232