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Diffstat (limited to 'doc/go_tutorial.html')
| -rw-r--r-- | doc/go_tutorial.html | 28 |
1 files changed, 17 insertions, 11 deletions
diff --git a/doc/go_tutorial.html b/doc/go_tutorial.html index 11e9b4ad7..ece22036a 100644 --- a/doc/go_tutorial.html +++ b/doc/go_tutorial.html @@ -238,14 +238,19 @@ started; for instance, <code>os.Args</code> is a slice used by the <p> <h2>An Interlude about Types</h2> <p> -Go has some familiar types such as <code>int</code> and <code>float</code>, which represent +Go has some familiar types such as <code>int</code> and <code>uint</code> (unsigned <code>int</code>), which represent values of the ''appropriate'' size for the machine. It also defines explicitly-sized types such as <code>int8</code>, <code>float64</code>, and so on, plus -unsigned integer types such as <code>uint</code>, <code>uint32</code>, etc. These are -distinct types; even if <code>int</code> and <code>int32</code> are both 32 bits in size, +unsigned integer types such as <code>uint</code>, <code>uint32</code>, etc. +These are distinct types; even if <code>int</code> and <code>int32</code> are both 32 bits in size, they are not the same type. There is also a <code>byte</code> synonym for <code>uint8</code>, which is the element type for strings. <p> +Floating-point types are always sized: <code>float32</code> and <code>float64</code>, +plus <code>complex64</code> (two <code>float32s</code>) and <code>complex128</code> +(two <code>float64s</code>). Complex numbers are outside the +scope of this tutorial. +<p> Speaking of <code>string</code>, that's a built-in type as well. Strings are <i>immutable values</i>—they are not just arrays of <code>byte</code> values. Once you've built a string <i>value</i>, you can't change it, although @@ -452,14 +457,15 @@ 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 </pre> <p> Conversions only work for simple cases such as converting <code>ints</code> of one -sign or size to another, and between <code>ints</code> and <code>floats</code>, 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. <p> @@ -538,9 +544,9 @@ We can use the factory to construct some familiar, exported variables of type <c <p> <pre> <!-- progs/file.go /var/ /^.$/ --> 24 var ( -25 Stdin = newFile(0, "/dev/stdin") -26 Stdout = newFile(1, "/dev/stdout") -27 Stderr = newFile(2, "/dev/stderr") +25 Stdin = newFile(syscall.Stdin, "/dev/stdin") +26 Stdout = newFile(syscall.Stdout, "/dev/stdout") +27 Stderr = newFile(syscall.Stderr, "/dev/stderr") 28 ) </pre> <p> @@ -663,7 +669,7 @@ something from the directory of installed packages. (Also, ''<code>file.go</code>'' must be compiled before we can import the package.) <p> -Now we can compile and run the program: +Now we can compile and run the program. On Unix, this would be the result: <p> <pre> $ 6g file.go # compile file package |