Go Basics - Revision history

Scott: /* Arrays and Slices */

2014-07-01T23:49:49Z

Arrays and Slices

← Older revision		Revision as of 23:49, 1 July 2014
Line 197:		Line 197:
	</source>		</source>

	=== Arrays ~~and Slices~~ ===		=== Arrays ===
	<source lang="go">		<source lang="go">
	var buffer [20]byte		var buffer [20]byte
Line 205:		Line 205:
	cities := [...]string{"Shanghai", "Mumbai", "Istanbul", "Beijing"}		cities := [...]string{"Shanghai", "Mumbai", "Istanbul", "Beijing"}
	cities[len(cities)-1] = "Karachi"		cities[len(cities)-1] = "Karachi"

	fmt.Println("Type Len Contents")		fmt.Println("Type Len Contents")
	fmt.Printf("%-8T %2d %v\n", buffer, len(buffer), buffer)		fmt.Printf("%-8T %2d %v\n", buffer, len(buffer), buffer)
Line 210:		Line 211:
	fmt.Printf("%-8T %2d %v\n", grid1, len(grid1), grid1)		fmt.Printf("%-8T %2d %v\n", grid1, len(grid1), grid1)
	fmt.Printf("%-8T %2d %v\n", grid2, len(grid2), grid2)		fmt.Printf("%-8T %2d %v\n", grid2, len(grid2), grid2)

			Type Len Contents
			[20]uint8 20 [0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0]
			[4]string 4 ["Shanghai" "Mumbai" "Istanbul" "Karachi"]
			[3][3]int 3 [[0 0 0] [8 6 2] [0 0 0]]
			[3][3]int 3 [[4 3 0] [8 6 2] [0 0 0]]
	</source>		</source>

Scott: /* Pointers */

2014-07-01T23:48:00Z

Pointers

@@ Line 195: / Line 195: @@
 swapAndProduct1(&i, &j, &product)
 fmt.Println(i, j, product)            // 9 5 45
 </source>

Scott: /* Pointers */

2014-03-08T00:42:04Z

Pointers

@@ Line 185: / Line 185: @@
 **ppi++    // Semantically the same as: (*(*ppi))++ and *(*ppi)++
 fmt.Println(z, pi, *pi, **ppi)  // 38 0xf840038100 38 38
 </source>

Scott: /* Commands */

2014-03-08T00:28:23Z

Commands

← Older revision		Revision as of 00:28, 8 March 2014
Line 42:		Line 42:
	go get github.com/nsf/gocode # grab a remote package and install it to $GOPATH/bin		go get github.com/nsf/gocode # grab a remote package and install it to $GOPATH/bin
	go get -u github.com/nsf/gocode # update to latest version of remote package		go get -u github.com/nsf/gocode # update to latest version of remote package
			gofmt myfile.go # output canonical code format
	</pre>		</pre>

Scott: /* Pointers */

2014-03-08T00:26:36Z

Pointers

← Older revision		Revision as of 00:26, 8 March 2014
Line 181:		Line 181:
	pi := &z // pi is of type *int (pointer to int)		pi := &z // pi is of type *int (pointer to int)
	ppi := &pi // ppi is of type **int (pointer to pointer to int)		ppi := &pi // ppi is of type **int (pointer to pointer to int)
	fmt.Println(z, pi, pi, *ppi)		fmt.Println(z, pi, pi, *ppi) // 37 0xf840038100 37 37
	*ppi++ // Semantically the same as: ((ppi))++ and (*ppi)++		*ppi++ // Semantically the same as: ((ppi))++ and (*ppi)++
	fmt.Println(z, pi, pi, *ppi)		fmt.Println(z, pi, pi, *ppi) // 38 0xf840038100 38 38
	</source>		</source>

Scott: /* Strings */

2014-03-08T00:26:07Z

Strings

← Older revision		Revision as of 00:26, 8 March 2014
Line 175:		Line 175:

	[[Go Strings\|Full page on Strings]]		[[Go Strings\|Full page on Strings]]


	=== Pointers ===		=== Pointers ===

Scott: /* Strings */

2014-03-08T00:25:46Z

Strings

← Older revision		Revision as of 00:25, 8 March 2014
Line 175:		Line 175:

	[[Go Strings\|Full page on Strings]]		[[Go Strings\|Full page on Strings]]


			=== Pointers ===
			<source lang="go">
			z := 37 // z is of type int
			pi := &z // pi is of type *int (pointer to int)
			ppi := &pi // ppi is of type **int (pointer to pointer to int)
			fmt.Println(z, pi, pi, *ppi)
			*ppi++ // Semantically the same as: ((ppi))++ and (*ppi)++
			fmt.Println(z, pi, pi, *ppi)
			</source>

Scott at 00:09, 14 February 2014

2014-02-14T00:09:41Z

← Older revision		Revision as of 00:09, 14 February 2014
Line 174:		Line 174:
	</source>		</source>

	~~==== Efficient String Append ====~~		[[Go Strings\|Full page on Strings]]
	~~<source lang="go">~~
	~~var buffer bytes.Buffer~~
	~~for {~~
	~~if piece, ok := getNextValidString(); ok {~~
	~~buffer.WriteString(piece)~~
	~~} else {~~
	~~break~~
	}
	}
	~~fmt.Print(buffer.String(), "\n")~~
	~~</source>~~

	~~==== Anatomy of a string ====~~
	[[~~File:anatomy_of_a_string.jpg]]~~
	~~<source lang="go">~~
	~~s := "naïve"~~
	~~fmt.Println(s, len(s)) // prints "naïve 6"~~
	~~</source>~~

	~~==== Slicing~~ Strings ~~====~~
	~~<source lang="go">~~
	~~line := "røde og gule sløjfer"~~
	~~i := strings.Index(line, " ") // Get the index of the first space~~
	~~firstWord := line[:i~~] ~~// Slice up to the first space~~
	~~j := strings.LastIndex(line, " ") // Get the index of the last space~~
	~~lastWord := line[j+1:~~] ~~// Slice from after the last space~~
	~~fmt.Println(firstWord, lastWord) // Prints: røde sløjfer~~
	~~</source>~~

	~~==== Anatomy of a string with whitespace ====~~
	~~[[File:anatomy_of_string_whitespace.jpg]]~~

	~~<source lang="go">~~
	~~line := "rå tørt\u2028vær"~~
	~~i := strings.IndexFunc(line, unicode.IsSpace) // i == 3~~
	~~firstWord := line[:i]~~
	~~j := strings.LastIndexFunc(line, unicode.IsSpace) // j == 9~~
	~~_, size := utf8.DecodeRuneInString(line[j:]) // size == 3~~
	~~lastWord := line[j+size:] // j + size == 12~~
	~~fmt.Println(firstWord, lastWord) // Prints: rå vær~~
	~~</source>~~

	~~==== <code>fmt</code> print functions ====~~
	~~<source lang="go">~~
	~~fmt.Errorf(format,args...) // Returns an error value containing a string~~
	~~fmt.Fprint\|Fprintf\|Fprintln(writer, ...) // Writes to writer~~
	~~fmt.Print\|Printf\|Println(args...) // Writes to os.Stdout~~
	~~fmt.Sprint\|Sprintf\|Sprintln(args...) // Returns a string~~
	~~/* Xprint(args...) concatenate args */~~
	~~/* Xprintf(format, args...) print using format */~~
	~~/* Xprintln(args...) print args separated by spaces, ending with newline */~~
	~~</source>~~
	~~All versions return number of bytes written, and an error or nil.~~

	~~==== <code>fmt</code> format specifiers ====~~
	~~<source lang="go">~~
	~~fmt.Printf("%t %t\n", true, false) // true false~~
	~~fmt.Printf("\|%b\|%9b\|%-9b\|%09b\|% 9b\|\n", 37, 37, 37, 37, 37) // \|100101\|···100101\|100101···\|000100101\|···100101\|~~
	~~fmt.Printf("\|%o\|%#o\|%# 8o\|%#+ 8o\|%+08o\|\n", 41, 41, 41, 41, -41) // \|51\|051\|·····051\|····+051\|-0000051\|~~
	~~i := 3931~~
	~~fmt.Printf("\|%x\|%X\|%8x\|%08x\|%#04X\|0x%04X\|\n", i, i, i, i, i, i) // \|f5b\|F5B\|·····f5b\|00000f5b\|0X0F5B\|0x0F5B\|~~
	~~i = 569~~
	~~fmt.Printf("\|$%d\|$%06d\|$%+06d\|\n", i, i, i) // \|$569\|$000569\|$+00569\|~~
	~~fmt.Printf("%d %#04x %U '%c'\n", 0x3A6, 934, '\u03A6', '\U000003A6') // 934·0x03a6·U+03A6·'Φ'~~
	~~x = 7194.84~~
	~~fmt.Printf("%e %f %g\n", x, x, x) // 7.194840e+03 7194.840000 7194.84~~
	~~fmt.Printf("%2.4f \n", x) // 7194.8400~~
	~~fmt.Printf("%s %q \n", "hi", "billy") // hi "billy"~~
	~~fmt.Printf("\|%10s\|%-10s\|\n", "billy", "billy") // \| billy\|billy \|~~
	~~fmt.Printf("%T, %T, %T\n", "billy", true, 24.35) // string, bool, float64~~
	~~s := "billy"~~
	~~fmt.Printf("%s's pointer is %p\n", s, &s) // billy's pointer is 0xf840028220~~
	~~</source>~~

Scott: /* fmt format specifiers */

2014-02-14T00:00:08Z

fmt format specifiers

← Older revision		Revision as of 00:00, 14 February 2014
Line 240:		Line 240:
	fmt.Printf("%d %#04x %U '%c'\n", 0x3A6, 934, '\u03A6', '\U000003A6') // 934·0x03a6·U+03A6·'Φ'		fmt.Printf("%d %#04x %U '%c'\n", 0x3A6, 934, '\u03A6', '\U000003A6') // 934·0x03a6·U+03A6·'Φ'
	x = 7194.84		x = 7194.84
	fmt.Printf("%e %f %g\n", x, x, x) // 7.194840e+03 7194.840000 7194.84		fmt.Printf("%e %f %g\n", x, x, x) // 7.194840e+03 7194.840000 7194.84
	fmt.Printf("%2.4f \n", x) // 7194.8400		fmt.Printf("%2.4f \n", x) // 7194.8400
			fmt.Printf("%s %q \n", "hi", "billy") // hi "billy"
			fmt.Printf("\|%10s\|%-10s\|\n", "billy", "billy") // \| billy\|billy \|
			fmt.Printf("%T, %T, %T\n", "billy", true, 24.35) // string, bool, float64
			s := "billy"
			fmt.Printf("%s's pointer is %p\n", s, &s) // billy's pointer is 0xf840028220
	</source>		</source>

Scott: /* fmt print functions */

2014-02-13T21:01:53Z

fmt print functions

← Older revision		Revision as of 21:01, 13 February 2014
Line 228:		Line 228:
	</source>		</source>
	All versions return number of bytes written, and an error or nil.		All versions return number of bytes written, and an error or nil.

			==== <code>fmt</code> format specifiers ====
			<source lang="go">
			fmt.Printf("%t %t\n", true, false) // true false
			fmt.Printf("\|%b\|%9b\|%-9b\|%09b\|% 9b\|\n", 37, 37, 37, 37, 37) // \|100101\|···100101\|100101···\|000100101\|···100101\|
			fmt.Printf("\|%o\|%#o\|%# 8o\|%#+ 8o\|%+08o\|\n", 41, 41, 41, 41, -41) // \|51\|051\|·····051\|····+051\|-0000051\|
			i := 3931
			fmt.Printf("\|%x\|%X\|%8x\|%08x\|%#04X\|0x%04X\|\n", i, i, i, i, i, i) // \|f5b\|F5B\|·····f5b\|00000f5b\|0X0F5B\|0x0F5B\|
			i = 569
			fmt.Printf("\|$%d\|$%06d\|$%+06d\|\n", i, i, i) // \|$569\|$000569\|$+00569\|
			fmt.Printf("%d %#04x %U '%c'\n", 0x3A6, 934, '\u03A6', '\U000003A6') // 934·0x03a6·U+03A6·'Φ'
			x = 7194.84
			fmt.Printf("%e %f %g\n", x, x, x) // 7.194840e+03 7194.840000 7194.84
			fmt.Printf("%2.4f \n", x) // 7194.8400
			</source>