README.md (3050B)
1 # cast 2 3 [](https://github.com/spf13/cast/actions/workflows/ci.yml) 4 [](https://pkg.go.dev/mod/github.com/spf13/cast) 5  6 [](https://goreportcard.com/report/github.com/spf13/cast) 7 8 Easy and safe casting from one type to another in Go 9 10 Don’t Panic! ... Cast 11 12 ## What is Cast? 13 14 Cast is a library to convert between different go types in a consistent and easy way. 15 16 Cast provides simple functions to easily convert a number to a string, an 17 interface into a bool, etc. Cast does this intelligently when an obvious 18 conversion is possible. It doesn’t make any attempts to guess what you meant, 19 for example you can only convert a string to an int when it is a string 20 representation of an int such as “8”. Cast was developed for use in 21 [Hugo](https://gohugo.io), a website engine which uses YAML, TOML or JSON 22 for meta data. 23 24 ## Why use Cast? 25 26 When working with dynamic data in Go you often need to cast or convert the data 27 from one type into another. Cast goes beyond just using type assertion (though 28 it uses that when possible) to provide a very straightforward and convenient 29 library. 30 31 If you are working with interfaces to handle things like dynamic content 32 you’ll need an easy way to convert an interface into a given type. This 33 is the library for you. 34 35 If you are taking in data from YAML, TOML or JSON or other formats which lack 36 full types, then Cast is the library for you. 37 38 ## Usage 39 40 Cast provides a handful of To_____ methods. These methods will always return 41 the desired type. **If input is provided that will not convert to that type, the 42 0 or nil value for that type will be returned**. 43 44 Cast also provides identical methods To_____E. These return the same result as 45 the To_____ methods, plus an additional error which tells you if it successfully 46 converted. Using these methods you can tell the difference between when the 47 input matched the zero value or when the conversion failed and the zero value 48 was returned. 49 50 The following examples are merely a sample of what is available. Please review 51 the code for a complete set. 52 53 ### Example ‘ToString’: 54 55 cast.ToString("mayonegg") // "mayonegg" 56 cast.ToString(8) // "8" 57 cast.ToString(8.31) // "8.31" 58 cast.ToString([]byte("one time")) // "one time" 59 cast.ToString(nil) // "" 60 61 var foo interface{} = "one more time" 62 cast.ToString(foo) // "one more time" 63 64 65 ### Example ‘ToInt’: 66 67 cast.ToInt(8) // 8 68 cast.ToInt(8.31) // 8 69 cast.ToInt("8") // 8 70 cast.ToInt(true) // 1 71 cast.ToInt(false) // 0 72 73 var eight interface{} = 8 74 cast.ToInt(eight) // 8 75 cast.ToInt(nil) // 0