github.com/FUSIONFoundation/efsn@v3.6.2-0.20200916075423-dbb5dd5d2cc7+incompatible/common/overflow/README.md (about) 1 [![Build Status](https://travis-ci.org/JohnCGriffin/overflow.png)](https://travis-ci.org/JohnCGriffin/overflow) 2 # overflow 3 Check for int/int8/int16/int64/int32 integer overflow in Golang arithmetic. 4 ### Install 5 ``` 6 go get github.com/johncgriffin/overflow 7 ``` 8 Note that because Go has no template types, the majority of repetitive code is 9 generated by overflow_template.sh. If you have to change an 10 algorithm, change it there and regenerate the Go code via: 11 ``` 12 go generate 13 ``` 14 ### Synopsis 15 16 ``` 17 package main 18 19 import "fmt" 20 import "math" 21 import "github.com/JohnCGriffin/overflow" 22 23 func main() { 24 25 addend := math.MaxInt64 - 5 26 27 for i := 0; i < 10; i++ { 28 sum, ok := overflow.Add(addend, i) 29 fmt.Printf("%v+%v -> (%v,%v)\n", 30 addend, i, sum, ok) 31 } 32 33 } 34 ``` 35 yields the output 36 ``` 37 9223372036854775802+0 -> (9223372036854775802,true) 38 9223372036854775802+1 -> (9223372036854775803,true) 39 9223372036854775802+2 -> (9223372036854775804,true) 40 9223372036854775802+3 -> (9223372036854775805,true) 41 9223372036854775802+4 -> (9223372036854775806,true) 42 9223372036854775802+5 -> (9223372036854775807,true) 43 9223372036854775802+6 -> (0,false) 44 9223372036854775802+7 -> (0,false) 45 9223372036854775802+8 -> (0,false) 46 9223372036854775802+9 -> (0,false) 47 ``` 48 49 For int, int64, and int32 types, provide Add, Add32, Add64, Sub, Sub32, Sub64, etc. 50 Unsigned types not covered at the moment, but such additions are welcome. 51 52 ### Stay calm and panic 53 54 There's a good case to be made that a panic is an unidiomatic but proper response. Iff you 55 believe that there's no valid way to continue your program after math goes wayward, you can 56 use the easier Addp, Mulp, Subp, and Divp versions which return the normal result or panic. 57 58 59 60 61 62 63