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Some folks might think: “you still use RCS”?!? And we will say, hey, at least we switched from SCCS to RCS back in … I think it was around 1994 ... at least we are keeping up! :-) :-) :-) Logs say that SCCS version 18 became RCS version 19 on 1994 March 18. RCS served us well. But now it is time to move on. And so we are switching to git. Calc releases produce a lot of file changes. In the 125 releases of calc since 1996, when I started managing calc releases, there have been 15473 file mods!
116 lines
3.6 KiB
Plaintext
116 lines
3.6 KiB
Plaintext
/*
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* prompt - eemonstration of some uses of prompt() and eval()
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*
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* Copyright (C) 1999 Ernest Bowen
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*
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* Calc is open software; you can redistribute it and/or modify it under
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* the terms of the version 2.1 of the GNU Lesser General Public License
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* as published by the Free Software Foundation.
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*
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* Calc is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
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* Public License for more details.
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*
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* A copy of version 2.1 of the GNU Lesser General Public License is
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* distributed with calc under the filename COPYING-LGPL. You should have
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* received a copy with calc; if not, write to Free Software Foundation, Inc.
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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* Under source code control: 1995/12/18 04:43:25
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* File existed as early as: 1995
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*
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* Share and enjoy! :-) http://www.isthe.com/chongo/tech/comp/calc/
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*/
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/*
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* Demonstration of some uses of prompt() and eval().
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*
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* adder() simulates a simple adding machine: starting with sum = 0,
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* each number entered in response to the ? prompt is added to sum
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* and the result displayed. Operation of adder() is ended by
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* entering "end", "exit" or "quit"; "end" returns to the level from
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* which adder() is called, e.g. with:
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*
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* for (;;) adder()
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*
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* entering "end" would start a new edition with sum = 0; "quit" and
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* "exit" return to the top level.
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*
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* Each response to ? is read as
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* a string terminated by a newline; the statements and expressions
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* in this string are compiled and evaluated as in function evaluation;
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* thus the string may include variables, assignments, functions, etc.
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* as in:
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*
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* 2 + 3
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* x = 2 + 3, x^3
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* x^2
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* local x = 2; while (x < 100) x *= 2; x % 100
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* x
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* exp(2, 1e-5)
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* sum
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* print sum^2;
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* 3; print sum^2;
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*
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* (Here the second line creates x as a global variable; the local
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* variable x in the fourth line has no effect on the global x. In
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* the last three lines, sum is the sum of numbers already entered, so
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* the third last line doubles the value of sum. The value returned
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* by "print sum^2;" is the null value, so the second last line adds
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* nothing to sum. The last line returns the value 3, i.e. the last
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* non-null value found for the expressions separated by semicolons,
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* so sum will be increased by 3 after the "print sum^2;" command
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* is executed. xxx The terminating semicolon is essential in the
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* last two lines. A command like eval("print 7;") is acceptable to
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* calc but eval("print 7") causes an exit from calc. xxx)
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*
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* If the value returned is not a number (e.g. the name of a list or matrix,
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* or if the string has syntax errors as in "2 + ", in which case the
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* value returned is an error value), the compile error messages and a
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* request for another number are displayed.
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*
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* Calling showvalues(str) assumes str defines a function of x as in:
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*
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* "sin(x)", "x^2 + 3*x", "exp(x, 1e-5)".
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*
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* Values of the function so defined are returned for values of x
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* entered in reponse to the ? prompt. Operation is terminated by
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* entering "end", "exit" or "quit".
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*/
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define adder() {
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global sum = 0;
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local s, t;
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for (;;) {
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s = prompt("? ");
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if (s == "end")
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break;
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t = eval(s);
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if (!isnum(t)) {
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print "Please enter a number";
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continue;
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}
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sum += t;
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print "\t":sum;
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}
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}
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global prompt_x;
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define showvalues(str) {
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local s;
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for (;;) {
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s = prompt("? ");
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if (s == "end")
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break;
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prompt_x = eval(s);
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if (!isnum(prompt_x)) {
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print "Please enter a number";
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continue;
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}
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print "\t":eval(str);
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}
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}
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