Implement Pic. It should return a slice of length dy, each element of which is a slice of dx 8-bit unsigned integers. When you run the program, it will display your picture, interpreting the integers as grayscale (well, bluescale) values. The choice…

The zero value of a slice is nil. A nil slice has a length and capacity of 0. (To learn more about slices, read the Slices: usage and internalsarticle.) package main import "fmt" func main() { var z []int fmt.Println(z, len(z), cap(z)) if z == n…

Slices are created with the make function. It works by allocating a zeroed array and returning a slice that refers to that array: a := make([]int, 5) // len(a)=5 To specify a capacity, pass a third argument to make: b := make([]int, 0, 5) // len(b)=0…

---恢复内容开始--- Slices can be re-sliced, creating a new slice value that points to the same array. The expression s[lo:hi] evaluates to a slice of the elements from lo through hi-1, inclusive. Thus s[lo:lo] is empty and s[lo:lo+1] has one element. packa…

Remember the picture generator you wrote earlier? Let's write another one, but this time it will return an implementation of image.Image instead of a slice of data. Define your own Image type, implement the necessary methods, and callpic.ShowImage. B…

Implement the following types and define ServeHTTP methods on them. Register them to handle specific paths in your web server. type String string type Struct struct { Greeting string Punct string Who string } For example, you should be able to regist…

Copy your Sqrt function from the earlier exercises and modify it to return an error value. Sqrt should return a non-nil error value when given a negative number, as it doesn't support complex numbers. Create a new type type ErrNegativeSqrt float64 an…

Let's have some fun with functions. Implement a fibonacci function that returns a function (a closure) that returns successive fibonacci numbers. package main import "fmt" // fibonacci is a function that returns // a function that returns an int…

Implement WordCount. It should return a map of the counts of each “word” in the string s. The wc.Test function runs a test suite against the provided function and prints success or failure. You might find strings.Fields helpful. package main import (…

As a simple way to play with functions and loops, implement the square root function using Newton's method. In this case, Newton's method is to approximate Sqrt(x) by picking a starting point z and then repeating: To begin with, just repeat that calc…