fix printing of fractionals (not scientific anymore), added -p flag

calc.go

@@ -1,5 +1,5 @@
 /*
-Copyright © 2023 Thomas von Dein
+Copyright © 2023-2024 Thomas von Dein
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -20,6 +20,7 @@ package main
 import (
 	"errors"
 	"fmt"
+	"math"
 	"regexp"
 	"sort"
 	"strconv"
@@ -35,6 +36,8 @@ type Calc struct {
 	showstack    bool
 	intermediate bool
 	notdone      bool // set to true as long as there are items left in the eval loop
+	precision    int
+
 	stack        *Stack
 	history      []string
 	completer    readline.AutoCompleter
@@ -91,6 +94,7 @@ Register variables:
 const (
 	//Commands  string = `dump reverse clear shift undo help history manual exit quit swap debug undebug nodebug batch nobatch showstack noshowstack vars`
 	Constants string = `Pi Phi Sqrt2 SqrtE SqrtPi SqrtPhi Ln2 Log2E Ln10 Log10E`
+	Precision int    = 2
 )
 
 // That way we can add custom functions to completion
@@ -150,7 +154,7 @@ func (c *Calc) GetCompleteCustomFuncalls() func(string) []string {
 }
 
 func NewCalc() *Calc {
-	c := Calc{stack: NewStack(), debug: false}
+	c := Calc{stack: NewStack(), debug: false, precision: Precision}
 
 	c.Funcalls = DefineFunctions()
 	c.BatchFuncalls = DefineBatchFunctions()
@@ -438,7 +442,16 @@ func (c *Calc) Result() float64 {
 			fmt.Print("= ")
 		}
 
-		fmt.Println(c.stack.Last()[0])
+		result := c.stack.Last()[0]
+		truncated := math.Trunc(result)
+		precision := c.precision
+
+		if result == truncated {
+			precision = 0
+		}
+
+		format := fmt.Sprintf("%%.%df\n", precision)
+		fmt.Printf(format, result)
 	}
 
 	return c.stack.Last()[0]

main.go

@@ -1,5 +1,5 @@
 /*
-Copyright © 2023 Thomas von Dein
+Copyright © 2023-2024 Thomas von Dein
 
 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
@@ -30,26 +30,27 @@ import (
 	lua "github.com/yuin/gopher-lua"
 )
 
-const VERSION string = "2.0.13"
+const VERSION string = "2.1.0"
 
 const Usage string = `This is rpn, a reverse polish notation calculator cli.
 
 Usage: rpn [-bdvh] [<operator>]
 
 Options:
-  -b, --batchmode     enable batch mode
-  -d, --debug         enable debug mode
-  -s, --stack         show last 5 items of the stack (off by default)
-  -i  --intermediate  print intermediate results
-  -m, --manual        show manual
-  -c, --config <file> load <file> containing LUA code
-  -v, --version       show version
-  -h, --help          show help
+  -b, --batchmode       enable batch mode
+  -d, --debug           enable debug mode
+  -s, --stack           show last 5 items of the stack (off by default)
+  -i  --intermediate    print intermediate results
+  -m, --manual          show manual
+  -c, --config <file>   load <file> containing LUA code
+  -p, --precision <int> floating point number precision (default 2)
+  -v, --version         show version
+  -h, --help            show help
 
 When <operator>  is given, batch  mode ist automatically  enabled. Use
 this only when working with stdin. E.g.: echo "2 3 4 5" | rpn +
 
-Copyright (c) 2023 T.v.Dein`
+Copyright (c) 2023-2024 T.v.Dein`
 
 func main() {
 	os.Exit(Main())
@@ -74,6 +75,7 @@ func Main() int {
 	flag.BoolVarP(&showmanual, "manual", "m", false, "show manual")
 	flag.StringVarP(&configfile, "config", "c",
 		os.Getenv("HOME")+"/.rpn.lua", "config file (lua format)")
+	flag.IntVarP(&calc.precision, "precision", "p", Precision, "floating point precision")
 
 	flag.Parse()
 

rpn.go

@@ -8,13 +8,15 @@ SYNOPSIS
         Usage: rpn [-bdvh] [<operator>]
     
         Options:
-          -b, --batchmode     enable batch mode
-          -d, --debug         enable debug mode
-          -s, --stack         show last 5 items of the stack (off by default)
-          -i  --intermediate  print intermediate results
-          -m, --manual        show manual
-          -v, --version       show version
-          -h, --help          show help
+          -b, --batchmode       enable batch mode
+          -d, --debug           enable debug mode
+          -s, --stack           show last 5 items of the stack (off by default)
+          -i  --intermediate    print intermediate results
+          -m, --manual          show manual
+          -c, --config <file>   load <file> containing LUA code
+          -p, --precision <int> floating point number precision (default 2)
+          -v, --version         show version
+          -h, --help            show help
     
         When <operator>  is given, batch  mode ist automatically  enabled. Use
         this only when working with stdin. E.g.: echo "2 3 4 5" | rpn +
@@ -309,6 +311,15 @@ EXTENDING RPN USING LUA
     So you can't open files, execute other programs or open a connection to
     the outside!
 
+CONFIGURATION
+    rpn can be configured via command line flags (see usage above). Most of
+    the flags are also available as interactive commands, such as "--batch"
+    has the same effect as the batch command.
+
+    The floating point number precision option "-p, --precision" however is
+    not available as interactive command, it MUST be configured on the
+    command line, if needed. The default precision is 2.
+
 GETTING HELP
     In interactive mode you can enter the help command (or ?) to get a short
     help along with a list of all supported operators and functions.
@@ -328,7 +339,7 @@ LICENSE
     This software is licensed under the GNU GENERAL PUBLIC LICENSE version
     3.
 
-    Copyright (c) 2023 by Thomas von Dein
+    Copyright (c) 2023-2024 by Thomas von Dein
 
     This software uses the following GO modules:
 

rpn.pod

@@ -7,13 +7,15 @@ rpn - Programmable command-line calculator using reverse polish notation
     Usage: rpn [-bdvh] [<operator>]
 
     Options:
-      -b, --batchmode     enable batch mode
-      -d, --debug         enable debug mode
-      -s, --stack         show last 5 items of the stack (off by default)
-      -i  --intermediate  print intermediate results
-      -m, --manual        show manual
-      -v, --version       show version
-      -h, --help          show help
+      -b, --batchmode       enable batch mode
+      -d, --debug           enable debug mode
+      -s, --stack           show last 5 items of the stack (off by default)
+      -i  --intermediate    print intermediate results
+      -m, --manual          show manual
+      -c, --config <file>   load <file> containing LUA code
+      -p, --precision <int> floating point number precision (default 2)
+      -v, --version         show version
+      -h, --help            show help
 
     When <operator>  is given, batch  mode ist automatically  enabled. Use
     this only when working with stdin. E.g.: echo "2 3 4 5" | rpn +
@@ -342,6 +344,16 @@ B<Please note, that io, networking and system stuff is not allowed
 though. So you can't open files, execute other programs or open a
 connection to the outside!>
 
+=head1 CONFIGURATION
+
+B<rpn> can be configured via command line flags (see usage
+above). Most of the flags are also available as interactive commands,
+such as C<--batch> has the same effect as the B<batch> command.
+
+The floating point number  precision option C<-p, --precision> however
+is not available as interactive command,  it MUST be configured on the
+command line, if needed. The default precision is 2.
+
 =head1 GETTING HELP
 
 In interactive mode you can enter the B<help> command (or B<?>) to get
@@ -364,7 +376,7 @@ L<https://github.com/TLINDEN/rpnc/issues>.
 
 This software is licensed under the GNU GENERAL PUBLIC LICENSE version 3.
 
-Copyright (c) 2023 by Thomas von Dein
+Copyright (c) 2023-2024 by Thomas von Dein
 
 This software uses the following GO modules:
 

t/cmdline-precision.txtar

@@ -0,0 +1,2 @@
+exec testrpn -p 4 2 3 /
+stdout '0.6667\n'