{"id":10008129,"date":"2023-08-22T12:59:07","date_gmt":"2023-08-22T04:59:07","guid":{"rendered":"https:\/\/blog.itmax.cn\/?p=10008129"},"modified":"2023-08-22T12:59:07","modified_gmt":"2023-08-22T04:59:07","slug":"go-%e9%9b%b6%e5%80%bc%e5%92%8c%e7%a9%ba%e5%80%bc%e7%9a%84%e5%88%a4%e6%96%ad%e9%97%ae%e9%a2%98","status":"publish","type":"post","link":"https:\/\/itmax.cn\/?p=10008129","title":{"rendered":"Go \u96f6\u503c\u548c\u7a7a\u503c\u7684\u5224\u65ad\u95ee\u9898"},"content":{"rendered":"

\u5927\u5bb6\u597d\uff0c\u6211\u662f\u714e\u9c7c\u3002<\/p>\n

\u524d\u6bb5\u65f6\u95f4\u5206\u4eab\u4e86\u300aGo \u5c06\u589e\u52a0\u5185\u7f6e\u7684\u96f6\u503c\u6807\u8bc6\u7b26 zero\uff01<\/a>\u300b\u7684\u65b0\u9884\u5b9a\u4e49\u6807\u8bc6\u7b26 zero<\/code>\u3002\u5bf9\u5e94\u7684\u7b7e\u540d\u5982\u4e0b\uff1a<\/p>\n

\/\/ zero is a predeclared identifier representing the zero value\n\/\/ for array and struct types.\nvar zero Type<\/code><\/pre>\n
\u6211\u539f\u60f3\u7740\u8fd8\u662f\u4e00\u4e2a\u6709\u4e00\u70b9\u70b9\u65b0\u6539\u53d8\u3002\u4e0d\u8fc7\u7efc\u5408\u5927\u5bb6\u610f\u89c1\u6765\u770b\uff0c\u7531\u4e8e\u53ea\u662f\u9488\u5bf9\u6570\u7ec4\uff08array\uff09\u548c\u7ed3\u6784\u4f53\uff08struct\uff09\uff0c\u8bb8\u591a\u540c\u5b66\u8868\u793a\u8fd9\u4e2a\u662f\u6bd4\u8f83\u9e21\u808b\u7684\u3002\u56e0\u4e3a\u4ecd\u7136\u65e0\u6cd5\u5f88\u597d\u7684\u89e3\u51b3 Go \u96f6\u503c\u548c\u7a7a\u503c\u7684\u8bc6\u522b\u95ee\u9898<\/strong>\uff0c\u5927\u5931\u6240\u671b\u3002<\/p>\n
\u672c\u6587\u662f\u5bf9\u96f6\u503c\u548c\u7a7a\u503c\u5224\u65ad\u73b0\u72b6\u8fdb\u884c\u68b3\u7406\u548c\u5206\u4eab\u3002<\/p>\n
\u5feb\u901f\u590d\u4e60\u96f6\u503c<\/h2>\n
\u57fa\u672c\u7c7b\u578b<\/h3>\n
var a int\nvar b bool\nvar c string\n\nfunc main() {\n    fmt.Printf("%+v\/n", a) \/\/ 0\n    fmt.Printf("%+v\/n", b) \/\/ false\n    fmt.Printf("%+v\/n", c) \/\/ ""\n}<\/code><\/pre>\n
\u590d\u5408\u7c7b\u578b<\/h3>\n
var a []int\nvar b map[string]int\nvar c [7]int\nvar d *int\nvar g chan int\nvar p Person\n\ntype Person struct {\n    Name string\n    Age  int\n}\n\nfunc main() {\n    fmt.Printf("%+v\/n", a) \/\/ []\n    fmt.Printf("%+v\/n", b) \/\/ map[]\n    fmt.Printf("%+v\/n", c) \/\/ [0 0 0 0 0 0 0]\n    fmt.Printf("%+v\/n", d) \/\/ <nil>\n    fmt.Printf("%+v\/n", g) \/\/ <nil>\n    fmt.Printf("%+v\/n", p) \/\/ {Name: Age:0}\n}<\/code><\/pre>\n
\u8fdb\u884c\u7a7a\u503c\u5224\u65ad<\/h2>\n
\u5728\u5b9e\u9645\u7684 Go \u4e1a\u52a1\u5e94\u7528\u4e2d\uff0c\u6211\u4eec\u9700\u8981\u5bf9\u6570\u636e\u7684\u96f6\u503c\u548c\u7a7a\u503c\u8fdb\u884c\u533a\u5206\uff0c\u4ee5\u4fbf\u4e8e\u5b9e\u73b0\u4e00\u4e9b\u7a7a\u503c\u7684\u4e1a\u52a1\u903b\u8f91\u5904\u7406\u3002<\/p>\n
\u5e38\u89c1\u7684\u6709\u4e24\u79cd\u505a\u6cd5\u3002\u5982\u4e0b\uff1a<\/p>\n
    \n
  1. \u5728\u53d8\u91cf\u58f0\u660e\u65f6\uff0c\u4f7f\u7528\u6307\u9488\u6765\u5904\u7406\uff0c\u5c06\u5176\u58f0\u660e\u4e3a\u6307\u9488\u7c7b\u578b\u3002<\/li>\n
  2. \u5728\u5b9a\u4e49\u53d8\u91cf\u7f3a\u7701\u503c\u65f6\uff0c\u9519\u5f00\u7c7b\u578b\u7684\u96f6\u503c\u3002\u4f8b\u5982\uff1aint \u96f6\u503c\u662f 0\uff0c\u4e1a\u52a1\u91cc\u5b57\u6bb5\u7f3a\u7701\u503c\u5b9a\u4e49\u4e3a 1 \u548c 2 \u7b49\u3002<\/li>\n<\/ol>\n
    \u7b2c\u4e00\u79cd\u662f\u7528\u7684\u6700\u591a\u7684\uff0c\u4e5f\u662f\u524d\u6587\u8bc4\u8bba\u533a\u5927\u5bb6\u6709\u6240\u63d0\u5230\u7684\u3002\u5bf9\u4e8e\u57fa\u7840\u7c7b\u578b\uff0c\u5177\u4f53\u7684\u4ee3\u7801\u793a\u4f8b\u5982\u4e0b\uff1a<\/p>\n
    var a *int\nvar b *bool\nvar c *string\n\nfunc main() {\n    if a == nil {\n        fmt.Print("\u714e\u9c7c")\n    }\n    if b == nil {\n        fmt.Print("\u8fdb")\n    }\n    if c == nil {\n        fmt.Print("\u8111\u5b50\u4e86")\n    }\n}<\/code><\/pre>\n
    \u8f93\u51fa\u7ed3\u679c\uff1a\u714e\u9c7c\u8fdb\u8111\u5b50\u4e86\u3002<\/p>\n
    \u5bf9\u4e8e\u590d\u5408\u7c7b\u578b\uff0c\u4e5f\u662f\u4e00\u6837\u7684\uff1a<\/p>\n
    var a []int\nvar b map[string]int\nvar g chan int\n\nvar c *[7]int\nvar d *int\nvar p *Person<\/code><\/pre>\n
    \u5bf9\u4e8e\u590d\u5408\u7c7b\u578b\u7684\u4e00\u4e9b\u503c\u7c7b\u578b\uff0c\u7531\u4e8e\u96f6\u503c\u6709\u53ef\u80fd\u662f\u7a0b\u5e8f\u8d4b\u7684\u503c\uff0c\u4e5f\u6709\u53ef\u80fd\u662f\u771f\u7a7a\u503c\u3002\u56e0\u6b64\u540c\u6837\u9700\u8981\u52a0\u4e0a\u6307\u9488\uff0c\u7528\u4e8e\u8bc6\u522b\u3002<\/p>\n
    \u5728 Go \u4e1a\u52a1\u7a0b\u5e8f\u4e0a\uff0c\u5927\u5bb6\u4e3a\u4e86\u89e3\u51b3\u8fd9\u4e2a\u96f6\u503c\u548c\u7a7a\u503c\u7684\u5224\u522b\u95ee\u9898\u3002\u4f1a\u91c7\u53d6\u7c7b\u4f3c\u7684\u65b9\u5f0f\u53bb\u7f16\u5199\u5305\u548c\u7a0b\u5e8f\u3002<\/p>\n
    \u5982\u4e0b\u4ee3\u7801\uff1a<\/p>\n
    type Person struct {\n    Name *string\n    Age  *int\n}\n\nfunc main() {\n    s := `{\n        "name": "\u714e\u9c7c"\n    }`\n\n    var p Person\n    err := json.Unmarshal([]byte(s), &p)\n    if err != nil {\n        fmt.Println(err)\n    }\n    fmt.Printf("p: %+v\/n", p)\n    fmt.Println(*p.Name)\n}<\/code><\/pre>\n
    \u8f93\u51fa\u7ed3\u679c\uff1a<\/p>\n
    p: {Name:0xc00010c380 Age:<nil>}\n\u714e\u9c7c<\/code><\/pre>\n
    \u53ef\u4ee5\u770b\u5230\u6240\u4f20\u5165\u7684 json \u5b57\u7b26\u4e32\u5e76\u4e0d\u5305\u542b age \u5b57\u6bb5\uff0c\u56e0\u6b64\u5176\u503c\u4e3a nil\u3002<\/p>\n
    \u5982\u679c\u662f\u4e3a\u7a7a\u5b57\u7b26\u4e32\uff1a<\/p>\n
    s := `{\n        "name": ""\n    }`<\/code><\/pre>\n
    \u89e3\u6790\u540e\u8f93\u51fa\u7684\u7ed3\u679c\u4e3a\uff1a<\/p>\n
    p: {Name:0xc000096380 Age:<nil>}\n<\/code><\/pre>\n
    \u4ee5\u6b64\u5c31\u53ef\u4ee5\u5b9e\u73b0\u7a7a\u503c\u548c\u96f6\u503c\u7684\u6709\u6548\u533a\u5206\uff0c\u4e0d\u518d\u4e3a\u6b64\u5224\u522b\u70e6\u607c\u592a\u591a\u3002<\/p>\n
    \u4f46\u4e5f\u5f15\u5165\u4e86\u4e00\u4e2a\u9ebb\u70e6\u7684\u70b9\uff0c\u5c31\u662f\u5728\u83b7\u53d6\u503c\u65f6\u9700\u8981\u4f7f\u7528 *p.Name<\/code> \u7684\u65b9\u5f0f\u3002\u5982\u679c\u5e0c\u671b \u201c\u5c4f\u853d\u201d \u8fd9\u4e2a\u7528\u6cd5\uff0c\u4e00\u822c\u8fd8\u4f1a\u518d\u505a\u4e00\u6b21\u51fd\u6570\u5c01\u88c5\u4f5c\u4e3a Getter \u7684\u65b9\u6cd5\u3002<\/p>\n
    \u65b0\u589e zero \u89e3\u51b3\u4ec0\u4e48\u95ee\u9898<\/h2>\n
    \u663e\u7136\u6211\u518d\u56de\u53bb\u770b\u5373\u5c06\u65b0\u52a0\u5165\u7684 zero<\/code> \u6807\u8bc6\u7b26\u65f6\uff0c\u4f1a\u53d1\u73b0\u4ed6\u80fd\u591f\u6210\u529f Go \u7684\u673a\u7f18\u662f\u5bf9\u96f6\u503c\u7684\u6bd4\u8f83\u5224\u65ad\uff0c\u800c\u5e76\u975e\u7a7a\u503c\u7684\u539f\u56e0\u3002<\/p>\n
    zero \u4f7f\u7528\u573a\u666f\u662f\uff1a<\/p>\n
    if val == zero(MyType) {}<\/code><\/pre>\n
    \u53c8\u6216\u662f\uff1a<\/p>\n
    func example[T any]() T {\n  \/\/ do something that returns an error...\n  if err != nil {\n    return zero(T)\n  }\n  \/\/...\n}<\/code><\/pre>\n
    \u8fd9\u4e48\u4e00\u68b3\u7406\uff0c\u53d1\u73b0\u786e\u5b9e\u548c\u6211\u4eec\u60f3\u8c61\u4e2d\u7684\u6709\u4e00\u5b9a\u7684\u5dee\u8ddd\u3002\u56e0\u4e3a\u6211\u4eec\u5728\u5b9e\u9645\u7684\u96f6\u503c\u548c\u7a7a\u503c\u7684\u5224\u65ad\u4e2d\uff0c\u66f4\u9700\u8981\u7684\u662f\u5bf9\u5185\u90e8\u5b57\u6bb5\u7684\u6570\u503c\u5224\u65ad\u4f8b\u5982\uff1a\u7ed3\u6784\u4f53\u91cc\u7684\u67d0\u4e9b\u5b57\u6bb5\uff0c\u6bd4\u8f83\u5c11\u662f\u53ea\u5bf9\u7ed3\u6784\u4f53\u672c\u8eab\u505a\u7a7a\u503c\u5224\u65ad\u3002<\/p>\n
    \u603b\u7ed3<\/h2>\n
    \u4eca\u5929\u6839\u636e\u5927\u5bb6\u70ed\u8bae\u7684\u53cd\u9988\uff0c\u91cd\u65b0\u68b3\u7406\u4e86 Go \u4e2d\u96f6\u503c\u548c\u7a7a\u503c\u7684\u73b0\u72b6\u548c\u5224\u65ad\u6280\u5de7\u3002\u611f\u89c9\u672c\u6b21 zero \u7684\u52a0\u5165\uff0c\u771f\u7684\u662f\u53ea\u52a0\u5f3a\u4e86\u7ed3\u6784\u4f53\u548c\u6570\u7ec4\u7c7b\u578b\u672c\u8eab\u7684\u96f6\u503c\u5224\u65ad\uff0c\u800c\u6ca1\u6709\u9488\u5bf9\u7a7a\u503c\u7684\u597d\u624b\u6bb5\u3002<\/p>\n
    \u7efc\u5408\u6765\u770b\uff0c\u8003\u8651\u5230\u89c4\u8303\uff08SPEC\uff09\u4e2d\u96f6\u503c\u662f\u5b98\u65b9\u7684\u89c4\u8303\u7ea6\u5b9a\uff0c\u6539\u53d8\u7684\u53ef\u80fd\u6027\u4e5f\u5f88\u4f4e\u4e86\u3002\u4e2a\u4eba\u611f\u89c9\u6838\u5fc3\u56e2\u961f\u65b0\u589e\u5224\u522b\u65b9\u5f0f\u6216\u4f18\u5316\u7684\u53ef\u80fd\u6027\u6bd4\u8f83\u4f4e\u3002<\/p>\n
    \u5927\u5bb6\u5e73\u65f6\u9664\u4e86\u4f7f\u7528\u6307\u9488\u548c\u9884\u5b9a\u4e49\u975e\u96f6\u503c\u7684\u679a\u4e3e\u503c\u5916\uff0c\u8fd8\u4f1a\u7528\u4ec0\u4e48\u65b9\u6cd5\u6765\u5224\u522b\u96f6\u503c\u548c\u7a7a\u503c\u5462\uff0c\u4e5f\u6b22\u8fce\u5927\u5bb6\u5206\u4eab\u4f60\u7684\u770b\u6cd5\uff01<\/p>\n
    \u6587\u7ae0\u6301\u7eed\u66f4\u65b0\uff0c\u53ef\u4ee5\u5fae\u4fe1\u641c\u3010\u8111\u5b50\u8fdb\u714e\u9c7c\u4e86\u3011\u9605\u8bfb\uff0c\u672c\u6587 GitHub<\/strong> github.com\/eddycjy\/blog<\/a> \u5df2\u6536\u5f55\uff0c\u5b66\u4e60 Go \u8bed\u8a00\u53ef\u4ee5\u770b Go \u5b66\u4e60\u5730\u56fe\u548c\u8def\u7ebf<\/a>\uff0c\u6b22\u8fce Star \u50ac\u66f4\u3002<\/p><\/blockquote>\n
    Go \u56fe\u4e66\u7cfb\u5217<\/h3>\n