README
¶
overflow
Check for int/int8/int16/int64/int32 integer overflow in Golang arithmetic.
Install
go get github.com/johncgriffin/overflow
Note that because Go has no template types, the majority of repetitive code is generated by overflow_template.sh. If you have to change an algorithm, change it there and regenerate the Go code via:
go generate
Synopsis
package main
import "fmt"
import "math"
import "github.com/JohnCGriffin/overflow"
func main() {
addend := math.MaxInt64 - 5
for i := 0; i < 10; i++ {
sum, ok := overflow.Add(addend, i)
fmt.Printf("%v+%v -> (%v,%v)\n",
addend, i, sum, ok)
}
}
yields the output
9223372036854775802+0 -> (9223372036854775802,true)
9223372036854775802+1 -> (9223372036854775803,true)
9223372036854775802+2 -> (9223372036854775804,true)
9223372036854775802+3 -> (9223372036854775805,true)
9223372036854775802+4 -> (9223372036854775806,true)
9223372036854775802+5 -> (9223372036854775807,true)
9223372036854775802+6 -> (0,false)
9223372036854775802+7 -> (0,false)
9223372036854775802+8 -> (0,false)
9223372036854775802+9 -> (0,false)
For int, int64, and int32 types, provide Add, Add32, Add64, Sub, Sub32, Sub64, etc.
Unsigned types not covered at the moment, but such additions are welcome.
Stay calm and panic
There's a good case to be made that a panic is an unidiomatic but proper response. Iff you believe that there's no valid way to continue your program after math goes wayward, you can use the easier Addp, Mulp, Subp, and Divp versions which return the normal result or panic.
Documentation
¶
Overview ¶
Package overflow offers overflow-checked integer arithmetic operations for int, int32, and int64. Each of the operations returns a result,bool combination. This was prompted by the need to know when to flow into higher precision types from the math.big library.
For instance, assuing a 64 bit machine:
10 + 20 -> 30 int(math.MaxInt64) + 1 -> -9223372036854775808
whereas
overflow.Add(10,20) -> (30, true) overflow.Add(math.MaxInt64,1) -> (0, false)
Add, Sub, Mul, Div are for int. Add64, Add32, etc. are specifically sized.
If anybody wishes an unsigned version, submit a pull request for code and new tests.
Index ¶
- func Add(a, b int) (int, bool)
- func Add16(a, b int16) (int16, bool)
- func Add16p(a, b int16) int16
- func Add32(a, b int32) (int32, bool)
- func Add32p(a, b int32) int32
- func Add64(a, b int64) (int64, bool)
- func Add64p(a, b int64) int64
- func Add8(a, b int8) (int8, bool)
- func Add8p(a, b int8) int8
- func Addp(a, b int) int
- func Div(a, b int) (int, bool)
- func Div16(a, b int16) (int16, bool)
- func Div16p(a, b int16) int16
- func Div32(a, b int32) (int32, bool)
- func Div32p(a, b int32) int32
- func Div64(a, b int64) (int64, bool)
- func Div64p(a, b int64) int64
- func Div8(a, b int8) (int8, bool)
- func Div8p(a, b int8) int8
- func Divp(a, b int) int
- func Mul(a, b int) (int, bool)
- func Mul16(a, b int16) (int16, bool)
- func Mul16p(a, b int16) int16
- func Mul32(a, b int32) (int32, bool)
- func Mul32p(a, b int32) int32
- func Mul64(a, b int64) (int64, bool)
- func Mul64p(a, b int64) int64
- func Mul8(a, b int8) (int8, bool)
- func Mul8p(a, b int8) int8
- func Mulp(a, b int) int
- func Quotient(a, b int) (int, int, bool)
- func Quotient16(a, b int16) (int16, int16, bool)
- func Quotient32(a, b int32) (int32, int32, bool)
- func Quotient64(a, b int64) (int64, int64, bool)
- func Quotient8(a, b int8) (int8, int8, bool)
- func Sub(a, b int) (int, bool)
- func Sub16(a, b int16) (int16, bool)
- func Sub16p(a, b int16) int16
- func Sub32(a, b int32) (int32, bool)
- func Sub32p(a, b int32) int32
- func Sub64(a, b int64) (int64, bool)
- func Sub64p(a, b int64) int64
- func Sub8(a, b int8) (int8, bool)
- func Sub8p(a, b int8) int8
- func Subp(a, b int) int
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func Quotient16 ¶
Quotient16 performs + operation on two int16 operands returning a quotient, a remainder and status
func Quotient32 ¶
Quotient32 performs + operation on two int32 operands returning a quotient, a remainder and status
func Quotient64 ¶
Quotient64 performs + operation on two int64 operands returning a quotient, a remainder and status
func Quotient8 ¶
Quotient8 performs + operation on two int8 operands returning a quotient, a remainder and status
Types ¶
This section is empty.
Source Files