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// Copyright 2016 The Cockroach Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
// implied. See the License for the specific language governing
// permissions and limitations under the License.
package apd_test
import (
"fmt"
"github.com/cockroachdb/apd/v3"
)
// ExampleOverflow demonstrates how to detect or error on overflow.
func ExampleContext_overflow() {
// Create a context that will overflow at 1e3.
c := apd.Context{
MaxExponent: 2,
Traps: apd.Overflow,
}
one := apd.New(1, 0)
d := apd.New(997, 0)
for {
res, err := c.Add(d, d, one)
fmt.Printf("d: %8s, overflow: %5v, err: %v\n", d, res.Overflow(), err)
if err != nil {
return
}
}
// Output:
// d: 998, overflow: false, err: <nil>
// d: 999, overflow: false, err: <nil>
// d: Infinity, overflow: true, err: overflow
}
// ExampleInexact demonstrates how to detect inexact operations.
func ExampleContext_inexact() {
d := apd.New(27, 0)
three := apd.New(3, 0)
c := apd.BaseContext.WithPrecision(5)
for {
res, err := c.Quo(d, d, three)
fmt.Printf("d: %7s, inexact: %5v, err: %v\n", d, res.Inexact(), err)
if err != nil {
return
}
if res.Inexact() {
return
}
}
// Output:
// d: 9.0000, inexact: false, err: <nil>
// d: 3.0000, inexact: false, err: <nil>
// d: 1.0000, inexact: false, err: <nil>
// d: 0.33333, inexact: true, err: <nil>
}
func ExampleContext_Quantize() {
input, _, _ := apd.NewFromString("123.45")
output := new(apd.Decimal)
c := apd.BaseContext.WithPrecision(10)
for i := int32(-3); i <= 3; i++ {
res, _ := c.Quantize(output, input, i)
fmt.Printf("%2v: %s", i, output)
if res != 0 {
fmt.Printf(" (%s)", res)
}
fmt.Println()
}
// Output:
// -3: 123.450
// -2: 123.45
// -1: 123.5 (inexact, rounded)
// 0: 123 (inexact, rounded)
// 1: 1.2E+2 (inexact, rounded)
// 2: 1E+2 (inexact, rounded)
// 3: 0E+3 (inexact, rounded)
}
func ExampleErrDecimal() {
c := apd.BaseContext.WithPrecision(5)
ed := apd.MakeErrDecimal(c)
d := apd.New(10, 0)
fmt.Printf("%s, err: %v\n", d, ed.Err())
ed.Add(d, d, apd.New(2, 1)) // add 20
fmt.Printf("%s, err: %v\n", d, ed.Err())
ed.Quo(d, d, apd.New(0, 0)) // divide by zero
fmt.Printf("%s, err: %v\n", d, ed.Err())
ed.Sub(d, d, apd.New(1, 0)) // attempt to subtract 1
// The subtraction doesn't occur and doesn't change the error.
fmt.Printf("%s, err: %v\n", d, ed.Err())
// Output:
// 10, err: <nil>
// 30, err: <nil>
// Infinity, err: division by zero
// Infinity, err: division by zero
}
// ExampleRoundToIntegralExact demonstrates how to use RoundToIntegralExact to
// check if a number is an integer or not. Note the variations between integer
// (which allows zeros after the decimal point) and strict (which does not). See
// the documentation on Inexact and Rounded.
func ExampleContext_RoundToIntegralExact() {
inputs := []string{
"123.4",
"123.0",
"123",
"12E1",
"120E-1",
"120E-2",
}
for _, input := range inputs {
d, _, _ := apd.NewFromString(input)
res, _ := apd.BaseContext.RoundToIntegralExact(d, d)
integer := !res.Inexact()
strict := !res.Rounded()
fmt.Printf("input: % 6s, output: %3s, integer: %5t, strict: %5t, res:", input, d, integer, strict)
if res != 0 {
fmt.Printf(" %s", res)
}
fmt.Println()
}
// Output:
// input: 123.4, output: 123, integer: false, strict: false, res: inexact, rounded
// input: 123.0, output: 123, integer: true, strict: false, res: rounded
// input: 123, output: 123, integer: true, strict: true, res:
// input: 12E1, output: 120, integer: true, strict: true, res:
// input: 120E-1, output: 12, integer: true, strict: false, res: rounded
// input: 120E-2, output: 1, integer: false, strict: false, res: inexact, rounded
}
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