1# cast
2
3[](https://github.com/spf13/cast/actions/workflows/ci.yaml)
4[](https://pkg.go.dev/mod/github.com/spf13/cast)
5
6[](https://goreportcard.com/report/github.com/spf13/cast)
7
8Easy and safe casting from one type to another in Go
9
10Don’t Panic! ... Cast
11
12## What is Cast?
13
14Cast is a library to convert between different go types in a consistent and easy way.
15
16Cast provides simple functions to easily convert a number to a string, an
17interface into a bool, etc. Cast does this intelligently when an obvious
18conversion is possible. It doesn’t make any attempts to guess what you meant,
19for example you can only convert a string to an int when it is a string
20representation 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
22for meta data.
23
24## Why use Cast?
25
26When working with dynamic data in Go you often need to cast or convert the data
27from one type into another. Cast goes beyond just using type assertion (though
28it uses that when possible) to provide a very straightforward and convenient
29library.
30
31If you are working with interfaces to handle things like dynamic content
32you’ll need an easy way to convert an interface into a given type. This
33is the library for you.
34
35If you are taking in data from YAML, TOML or JSON or other formats which lack
36full types, then Cast is the library for you.
37
38## Usage
39
40Cast provides a handful of To_____ methods. These methods will always return
41the desired type. **If input is provided that will not convert to that type, the
420 or nil value for that type will be returned**.
43
44Cast also provides identical methods To_____E. These return the same result as
45the To_____ methods, plus an additional error which tells you if it successfully
46converted. Using these methods you can tell the difference between when the
47input matched the zero value or when the conversion failed and the zero value
48was returned.
49
50The following examples are merely a sample of what is available. Please review
51the 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
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