diff options
Diffstat (limited to 'doc/go_tutorial.txt')
| -rw-r--r-- | doc/go_tutorial.txt | 22 |
1 files changed, 14 insertions, 8 deletions
diff --git a/doc/go_tutorial.txt b/doc/go_tutorial.txt index 9c08bd278..5eea3c980 100644 --- a/doc/go_tutorial.txt +++ b/doc/go_tutorial.txt @@ -189,14 +189,19 @@ started; for instance, "os.Args" is a slice used by the An Interlude about Types ---- -Go has some familiar types such as "int" and "float", which represent +Go has some familiar types such as "int" and "uint" (unsigned "int"), which represent values of the ''appropriate'' size for the machine. It also defines explicitly-sized types such as "int8", "float64", and so on, plus -unsigned integer types such as "uint", "uint32", etc. These are -distinct types; even if "int" and "int32" are both 32 bits in size, +unsigned integer types such as "uint", "uint32", etc. +These are distinct types; even if "int" and "int32" are both 32 bits in size, they are not the same type. There is also a "byte" synonym for "uint8", which is the element type for strings. +Floating-point types are always sized: "float32" and "float64", +plus "complex64" (two "float32s") and "complex128" +(two "float64s"). Complex numbers are outside the +scope of this tutorial. + Speaking of "string", that's a built-in type as well. Strings are <i>immutable values</i>—they are not just arrays of "byte" values. Once you've built a string <i>value</i>, you can't change it, although @@ -362,13 +367,14 @@ language specification but here are some illustrative examples: a := uint64(0) // equivalent; uses a "conversion" i := 0x1234 // i gets default type: int var j int = 1e6 // legal - 1000000 is representable in an int - x := 1.5 // a float + x := 1.5 // a float64, the default type for floating constants i3div2 := 3/2 // integer division - result is 1 - f3div2 := 3./2. // floating point division - result is 1.5 + f3div2 := 3./2. // floating-point division - result is 1.5 Conversions only work for simple cases such as converting "ints" of one -sign or size to another, and between "ints" and "floats", plus a few other -simple cases. There are no automatic numeric conversions of any kind in Go, +sign or size to another and between integers and floating-point numbers, +plus a couple of other instances outside the scope of a tutorial. +There are no automatic numeric conversions of any kind in Go, other than that of making constants have concrete size and type when assigned to a variable. @@ -482,7 +488,7 @@ something from the directory of installed packages. (Also, ''"file.go"'' must be compiled before we can import the package.) -Now we can compile and run the program: +Now we can compile and run the program. On Unix, this would be the result: $ 6g file.go # compile file package $ 6g helloworld3.go # compile main package |