{"id":18513,"date":"2025-07-14T15:13:10","date_gmt":"2025-07-14T07:13:10","guid":{"rendered":"https:\/\/blog.ywdevops.cn\/?p=18513"},"modified":"2025-07-16T18:37:08","modified_gmt":"2025-07-16T10:37:08","slug":"dart-2","status":"publish","type":"post","link":"https:\/\/blog.ywdevops.cn\/index.php\/2025\/07\/14\/dart-2\/","title":{"rendered":"Dart\u6570\u636e\u7c7b\u578b"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">Dart \u8bed\u8a00\u5bf9\u4ee5\u4e0b\u7c7b\u578b\u6709\u7279\u6b8a\u652f\u6301\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u6570\u5b57(int\uff0cdouble)<\/li>\n\n\n\n<li>\u5b57\u7b26\u4e32(String)<\/li>\n\n\n\n<li>\u5e03\u5c14(bool)<\/li>\n\n\n\n<li>\u8bb0\u5f55((value1,value2))<\/li>\n\n\n\n<li>\u51fd\u6570(Function)<\/li>\n\n\n\n<li>\u5217\u8868(List\uff0c\u4e5f\u53eb\u6570\u7ec4)<\/li>\n\n\n\n<li>\u96c6\u5408(Set)<\/li>\n\n\n\n<li>\u6620\u5c04(Map)<\/li>\n\n\n\n<li><a href=\"https:\/\/dart.ac.cn\/language\/built-in-types#runes-and-grapheme-clusters\">Runes<\/a>&nbsp;(<code>Runes<\/code>\uff1b\u5e38\u88ab&nbsp;<code>characters<\/code>&nbsp;API \u66ff\u6362)<\/li>\n\n\n\n<li>symbol(symbol)<\/li>\n\n\n\n<li>\u503cnull (Null)<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u56e0\u4e3a Dart \u4e2d\u7684\u6bcf\u4e2a\u53d8\u91cf\u90fd\u6307\u5411\u4e00\u4e2a\u5bf9\u8c61&#8211;&gt;\u4e00\u4e2a<em>\u7c7b<\/em>\u7684\u5b9e\u4f8b&#8211;&gt;\u4f60\u901a\u5e38\u53ef\u4ee5\u4f7f\u7528<em>\u6784\u9020\u51fd\u6570<\/em>\u6765\u521d\u59cb\u5316\u53d8\u91cf\u3002\u4e00\u4e9b\u5185\u7f6e\u7c7b\u578b\u6709\u81ea\u5df1\u7684\u6784\u9020\u51fd\u6570\u3002\u4f8b\u5982\uff0c\u4f60\u53ef\u4ee5\u4f7f\u7528&nbsp;<code>Map()<\/code>&nbsp;\u6784\u9020\u51fd\u6570\u521b\u5efa\u4e00\u4e2a\u6620\u5c04<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd8\u6709\u4e00\u4e9b\u5176\u4ed6\u7c7b\u578b\u5728 Dart \u8bed\u8a00\u4e2d\u4e5f\u626e\u6f14\u7740\u7279\u6b8a\u89d2\u8272\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><code>Object<\/code>\uff1a\u9664&nbsp;<code>Null<\/code>&nbsp;\u5916\u6240\u6709 Dart \u7c7b\u7684\u8d85\u7c7b<\/li>\n\n\n\n<li><code>Enum<\/code>\uff1a\u6240\u6709\u679a\u4e3e\u7684\u8d85\u7c7b<\/li>\n\n\n\n<li><code>Future<\/code>&nbsp;\u548c&nbsp;<code>Stream<\/code>\uff1a\u7528\u4e8e<a href=\"https:\/\/dart.ac.cn\/language\/async\">\u5f02\u6b65\u7f16\u7a0b<\/a><\/li>\n\n\n\n<li><code>Iterable<\/code>\uff1a\u7528\u4e8e<a href=\"https:\/\/dart.ac.cn\/libraries\/dart-core#iteration\">for-in \u5faa\u73af<\/a>\u548c\u540c\u6b65<a href=\"https:\/\/dart.ac.cn\/language\/functions#generators\">\u751f\u6210\u5668\u51fd\u6570<\/a><\/li>\n\n\n\n<li><code>Never<\/code>\uff1a\u8868\u793a\u8868\u8fbe\u5f0f\u6c38\u8fdc\u65e0\u6cd5\u6210\u529f\u5b8c\u6210\u6c42\u503c\u3002\u6700\u5e38\u7528\u4e8e\u603b\u662f\u629b\u51fa\u5f02\u5e38\u7684\u51fd\u6570<\/li>\n\n\n\n<li><code>dynamic<\/code>\uff1a\u8868\u793a\u4f60\u5e0c\u671b\u7981\u7528\u9759\u6001\u68c0\u67e5\u3002\u901a\u5e38\u4f60\u5e94\u8be5\u6539\u7528&nbsp;<code>Object<\/code>&nbsp;\u6216&nbsp;<code>Object?<\/code><\/li>\n\n\n\n<li><code>void<\/code>\uff1a\u8868\u793a\u4e00\u4e2a\u503c\u6c38\u8fdc\u4e0d\u4f1a\u88ab\u4f7f\u7528\u3002\u5e38\u7528\u4e8e\u4f5c\u4e3a\u8fd4\u56de\u7c7b\u578b<\/li>\n<\/ul>\n\n\n\n<p class=\"has-text-align-center wp-block-paragraph\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-purple-color\">\u6570\u5b57<\/mark><\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Dart \u6570\u5b57\u6709\u4e24\u79cd\u7c7b\u578b\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>int\uff1a\u4e0d\u5927\u4e8e 64 \u4f4d\u7684\u6574\u6570\u503c\uff0c\u5728\u539f\u751f\u5e73\u53f0\uff0c\u503c\u7684\u8303\u56f4\u662f -2<sup>63<\/sup>&nbsp;\u5230 2<sup>63<\/sup>&nbsp;&#8211; 1\u3002\u5728 Web \u4e0a\uff0c\u6574\u6570\u503c\u8868\u793a\u4e3a JavaScript \u6570\u5b57\uff08\u6ca1\u6709\u5c0f\u6570\u90e8\u5206\u7684 64 \u4f4d\u6d6e\u70b9\u503c\uff09\uff0c\u8303\u56f4\u662f -2<sup>53<\/sup>&nbsp;\u5230 2<sup>53<\/sup>&nbsp;&#8211; 1<\/li>\n\n\n\n<li>double\uff1a64\u4f4d(\u53cc\u7cbe\u5ea6)\u6d6e\u70b9\u6570<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><code>int<\/code>&nbsp;\u548c&nbsp;<code>double<\/code>&nbsp;\u90fd\u662f&nbsp;<a href=\"https:\/\/api.dart.ac.cn\/dart-core\/num-class.html\"><code>num<\/code><\/a>&nbsp;\u7684\u5b50\u7c7b\u578b\u3002num \u7c7b\u578b\u5305\u542b\u57fa\u672c\u8fd0\u7b97\u7b26\uff0c\u4f8b\u5982 +\u3001-\u3001\/ \u548c *\uff0c\u4ee5\u53ca&nbsp;<code>abs()<\/code>\u3001<code>ceil()<\/code>&nbsp;\u548c&nbsp;<code>floor()<\/code>&nbsp;\u7b49\u65b9\u6cd5\u3002\uff08\u4f4d\u8fd0\u7b97\u7b26\uff0c\u5982 &gt;&gt;\uff0c\u5b9a\u4e49\u5728&nbsp;<code>int<\/code>&nbsp;\u7c7b\u4e2d\u3002\uff09\u5982\u679c num \u53ca\u5176\u5b50\u7c7b\u578b\u6ca1\u6709\u4f60\u60f3\u8981\u7684\u529f\u80fd\uff0c<a href=\"https:\/\/api.dart.ac.cn\/dart-math\/dart-math-library.html\"><code>dart:math<\/code><\/a>&nbsp;\u5e93\u53ef\u80fd\u4f1a\u6709<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e0b\u9762\u662f\u58f0\u660e\u6574\u6570\u7c7b\u578b\u7684\u53d8\u91cf\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>var a = 100; \u6216 int a = 100;<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e0b\u9762\u662f\u58f0\u660edouble\u7c7b\u578b\u7684\u53d8\u91cf\uff0c\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>double a = 1.1;   \/\/\u5c0f\u6570<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e0b\u9762\u662f\u58f0\u660enum\u7c7b\u578b\uff0c\u6b64\u65f6\u53d8\u91cf\u53ef\u4ee5\u662fint\u4e5f\u53ef\u4ee5\u662fdouble,\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>num i = 10;\ni = i + 1.5;   \/\/i=11.5<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u6574\u6570\u53d8\u91cf\u4f1a\u81ea\u52a8\u8f6c\u6362\u4e3adouble\uff0c\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>doublt i = 10;\nprint(i); \/\/10.0<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u5c06\u5b57\u7b26\u4e32\u8f6c\u6362\u4e3a\u6574\u6570\uff0c\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>String s = '100';\nint i = int.parse(s); \/\/i=100<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u5c06\u5b57\u7b26\u4e32\u8f6c\u6362\u4e3a\u6d6e\u70b9\u6570\uff0c\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>String s = '100';\ndouble d = double.parse(s);\/\/d=100.0<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u5c06\u6574\u6570\u8f6c\u6362\u4e3a\u5b57\u7b26\u4e32\uff0c\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>int i = 100;\nString s = i.toString();\/\/ s = '100'<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u5c06double\u8f6c\u6362\u4e3a\u5b57\u7b26\u4e32\uff0c\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>double d = 10.586;\nString s = d.toStringAsFixed(2); \/\/s=10.59 \u4fdd\u75592\u4f4d\u5c0f\u6570\u5e76\u56db\u820d\u4e94\u5165<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u53ef\u4ee5\u4f7f\u7528\u4e00\u4e2a\u6216\u591a\u4e2a\u4e0b\u5212\u7ebf (<code>_<\/code>) \u4f5c\u4e3a\u6570\u5b57\u5206\u9694\u7b26\uff0c\u4f7f\u957f\u6570\u5b57\u5b57\u9762\u91cf\u66f4\u6613\u8bfb\uff0c\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>var i = 123_345_456_678  \/\/Dart\u7248\u672c\u8981\u8fbe\u52303.6<\/code><\/pre>\n\n\n\n<p class=\"has-text-align-center wp-block-paragraph\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-purple-color\">\u5b57\u7b26\u4e32<\/mark><\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">1\u3001\u53ef\u4ee5\u4f7f\u7528\u5355\u5f15\u53f7\u6216\u53cc\u5f15\u53f7\u521b\u5efa\u5b57\u7b26\u4e32\uff0c\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>var s1 = 'Single quotes work well for string literals.';\nvar s2 = \"Double quotes work just as well.\";\nvar s3 = 'It\\'s easy to escape the string delimiter.'; \/\/\u8981\u8f6c\u4e49\u5355\u5f15\u53f7\nvar s4 = \"It's even easier to use the other delimiter.\";\/\/\u4e0d\u7528\u8f6c\u4e49<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">2\u3001\u53ef\u4ee5\u4f7f\u7528&nbsp;<code>${<\/code><em><code>expression<\/code><\/em><code>}<\/code>&nbsp;\u5c06\u8868\u8fbe\u5f0f\u7684\u503c\u653e\u5165<strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-red-color\">\u5b57\u7b26\u4e32<\/mark><\/strong>\u4e2d\uff0c\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>int a = 100;\nint b = 200;\nString c = \"${a + b}\"; \/\/\u5b57\u7b26\u4e32\u63d2\u503c\uff0c\u63a5\u6536\u53d8\u91cf\u53ea\u80fd\u662f\u5b57\u7b26\u4e32<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">3\u3001\u5982\u679c\u8868\u8fbe\u5f0f\u662f\u4e00\u4e2a\u6807\u8bc6\u7b26\uff0c\u4f60\u53ef\u4ee5\u7701\u7565&nbsp;<code>{}<\/code>\uff0c\u5982\u56fe\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>int a = 100;\nString c = \"$a\";   \/\/\u7701\u7565{}<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">4\u3001\u4f7f\u7528\u201c==\u201d\u6765\u5224\u65ad\u4e24\u4e2a\u5b57\u7b26\u4e32\u662f\u5426\u76f8\u7b49\uff0c\u76f8\u7b49\u8fd4\u56detrue\uff0c\u5982\u56fe\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>String a = 'hello';\nString b = 'hello';\nprint(a ==b );   \/\/true<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">5\u3001\u4f7f\u7528\u76f8\u90bb\u7684\u5b57\u7b26\u4e32\u5b57\u9762\u91cf\u6216\u8005\u201d+\u201c\u6765\u8fde\u63a5\u5b57\u7b26\u4e32\uff0c\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>String a = 'hello';\nString b = 'world';\nString c = \"$a\" + \"$b\"; \/\/\u6216\u8005\"$a$b\"\u4e5f\u53ef\u4ee5\u8fde\u63a5\u5b57\u7b26\u4e32<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">6\u3001\u8981\u521b\u5efa\u591a\u884c\u5b57\u7b26\u4e32\uff0c\u8bf7\u4f7f\u7528\u5355\u5f15\u53f7\u6216\u53cc\u5f15\u53f7\u7684\u4e09\u91cd\u5f15\u53f7\uff0c\u6bd4\u5982\uff1a\u2018\u2019\u2018 \u2018\u2019\u2018 \u548c\u201c\u201d\u201c \u201d\u201c\u201d\uff0c\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>String a = \"\"\"hello\n     world\n     beijing\n     shenzhen\"\"\";\n\u6216\u8005\nString a = '''hello\n     world\n     beijing\n     shenzhen''';<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">7\u3001\u53ef\u4ee5\u5728\u5b57\u7b26\u4e32\u524d\u9762\u52a0\u201cr\u201d \u6765\u83b7\u53d6\u539f\u59cb\u5b57\u7b26\u4e32\uff0c\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>String a = r'hello \\n  world'; \/\/a=hello \\n  world,\u4fdd\u7559\u4e86\\n<\/code><\/pre>\n\n\n\n<p class=\"has-text-align-center wp-block-paragraph\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-purple-color\">\u5e03\u5c14<\/mark><\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Dart \u6709\u4e00\u4e2a\u540d\u4e3a&nbsp;<code>bool<\/code>&nbsp;\u7684\u7c7b\u578b\u3002\u53ea\u6709\u4e24\u4e2a\u5bf9\u8c61\u5c5e\u4e8e bool \u7c7b\u578b\uff1a\u5e03\u5c14\u5b57\u9762\u91cf&nbsp;<code>true<\/code>&nbsp;\u548c&nbsp;<code>false<\/code>\uff0c\u5b83\u4eec\u90fd\u662f\u7f16\u8bd1\u65f6\u5e38\u91cf<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Dart \u7684\u7c7b\u578b\u5b89\u5168\u610f\u5473\u7740\u4f60\u4e0d\u80fd\u4f7f\u7528\u8bf8\u5982&nbsp;<code>if&nbsp;(<em>\u975e\u5e03\u5c14\u503c<\/em>)<\/code>&nbsp;\u6216&nbsp;<code>assert&nbsp;(<em>\u975e\u5e03\u5c14\u503c<\/em>)<\/code>&nbsp;\u8fd9\u6837\u7684\u4ee3\u7801\u3002\u800c\u662f\u8981\u663e\u5f0f\u5730\u68c0\u67e5\u503c\uff0c\u5982\u4e0b\uff1a<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">1\u3001\u5224\u65ad\u5b57\u7b26\u4e32\u662f\u5426\u4e3a\u7a7a\uff0c\u5982\u56fe\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"651\" height=\"106\" src=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/9-4.png\" alt=\"\" class=\"wp-image-18542\" srcset=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/9-4.png 651w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/9-4-300x49.png 300w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/9-4-600x98.png 600w\" sizes=\"auto, (max-width: 651px) 100vw, 651px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"656\" height=\"143\" src=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/1-6.png\" alt=\"\" class=\"wp-image-18543\" srcset=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/1-6.png 656w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/1-6-300x65.png 300w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/1-6-600x131.png 600w\" sizes=\"auto, (max-width: 656px) 100vw, 656px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">assert\u662f\u4e00\u4e2a\u5728\u5f00\u53d1\u6d4b\u8bd5\u9636\u6bb5\u7528\u6765\u8c03\u8bd5\u4ee3\u7801\u7684\u65ad\u8a00\u51fd\u6570\uff0c\u53ef\u7528\u6765\u5224\u65ad\u5e03\u5c14\u503c\uff0c\u8981\u60f3\u8ba9asser\u751f\u6548\uff0c\u9700\u8981dart run &#8211;enable-asserts\u547d\u4ee4\u624d\u884c<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">2\u3001\u4e0b\u9762\u68c0\u67e5\u662f\u5426\u4e3a0\uff0c\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>var hitPoints = 0;\nassert(hitPoints == 0);<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">3\u3001\u4e0b\u9762\u68c0\u67e5\u662f\u5426\u4e3anull\uff0c\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>var unicorn = null;\nassert(unicorn == null);<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">4\u3001\u68c0\u67e5\u4e00\u4e2a\u503c\u4e0d\u662f\u4e00\u4e2a\u6570\u5b57\uff0c\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>var iMeantToDoThis = 0 \/ 0;\nassert(iMeantToDoThis.isNaN);<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\"><code>isNaN<\/code> \u662f\u4e00\u4e2a\u5e03\u5c14\u5c5e\u6027\uff0c\u7528\u4e8e\u68c0\u67e5\u4e00\u4e2a\u6570\u503c\u662f\u5426\u662f\u201c\u975e\u6570\u5b57\u201d\uff0cNan\u5168\u79f0\u662fNot a number\uff0c\u662f\u4e00\u4e2a\u7279\u6b8a\u7684\u6d6e\u70b9\u6570\u503c\uff0c\u8868\u793a\u201c\u4e0d\u662f\u4e00\u4e2a\u6570\u5b57\u201d\u7684\u72b6\u6001\uff0c\u901a\u5e38\u5728\u6570\u5b66\u8fd0\u7b97\u4e2d\u51fa\u73b0\u65e0\u6548\u6216\u672a\u5b9a\u4e49\u7684\u7ed3\u679c\u65f6\u4ea7\u751f<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><code>isNaN<\/code> \u662f <code>double<\/code> \u7c7b\u578b\u7684\u4e00\u4e2a\u5c5e\u6027\uff0c\u8fd4\u56de\u4e00\u4e2a\u5e03\u5c14\u503c\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u5982\u679c\u8be5\u503c\u662f NaN\uff0c\u5219\u8fd4\u56de <code>true<\/code><\/li>\n\n\n\n<li>\u5982\u679c\u8be5\u503c\u662f\u4e00\u4e2a\u6709\u6548\u7684\u6570\u5b57\uff0c\u5219\u8fd4\u56de <code>false<\/code><\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e0b\u9762\u4f8b\u5b50\u5224\u65ad\u4e24\u4e2a\u53d8\u91cf\u662f\u4e0d\u662f\u6570\u5b57\uff0c\u5982\u56fe\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"649\" height=\"143\" src=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/2-6.png\" alt=\"\" class=\"wp-image-18554\" srcset=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/2-6.png 649w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/2-6-300x66.png 300w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/2-6-600x132.png 600w\" sizes=\"auto, (max-width: 649px) 100vw, 649px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"651\" height=\"76\" src=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/3-6.png\" alt=\"\" class=\"wp-image-18555\" srcset=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/3-6.png 651w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/3-6-300x35.png 300w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/3-6-600x70.png 600w\" sizes=\"auto, (max-width: 651px) 100vw, 651px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\"><code>double.nan<\/code> \u662f\u4e00\u4e2a\u7279\u6b8a\u7684\u5e38\u91cf\uff0c\u8868\u793a\u201c\u975e\u6570\u5b57\u201d\uff08NaN\uff0c\u5373 Not-a-Number\uff09\u3002\u5b83\u662f\u4e00\u4e2a <code>double<\/code> \u7c7b\u578b\u7684\u503c\uff0c\u7528\u4e8e\u8868\u793a\u65e0\u6548\u6216\u672a\u5b9a\u4e49\u7684\u6d6e\u70b9\u6570\u8fd0\u7b97\u7ed3\u679c<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">NaN \u662f\u552f\u4e00\u4e00\u4e2a\u4e0d\u7b49\u4e8e\u81ea\u8eab\u7684\u503c\u3002\u56e0\u6b64\uff0c<code>NaN == NaN<\/code> \u7684\u7ed3\u679c\u662f <code>false<\/code>\uff0c\u56e0\u6b64\u5982\u679c\u8981\u68c0\u67e5\u4e00\u4e2a\u503c\u662f\u5426\u4e3aNaN\uff0c\u8981\u4f7f\u7528isNaN\uff0c\u800c\u4e0d\u662f==<\/p>\n\n\n\n<p class=\"has-text-align-center wp-block-paragraph\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-purple-color\">Symbol<\/mark><\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><code>Symbol<\/code>\u00a0\u7684\u4f7f\u7528\u9891\u7387\u76f8\u5bf9\u8f83\u4f4e\uff0c\u901a\u5e38\u51fa\u73b0\u5728\u4e00\u4e9b\u200b<strong>\u200b\u9ad8\u7ea7\u6216\u7279\u5b9a\u573a\u666f\u200b<\/strong>\u200b\u4e2d\uff0c<code>Symbol<\/code>\u00a0\u662f Dart \u4e2d\u7684\u4e00\u79cd\u200b<strong>\u200b\u7f16\u8bd1\u65f6\u5e38\u91cf\u200b<\/strong>\u200b\u7c7b\u578b\uff0c\u7528\u4e8e\u8868\u793a\u7a0b\u5e8f\u4e2d\u7684\u200b<strong>\u200b\u6807\u8bc6\u7b26\u540d\u79f0\u200b<\/strong>\u200b\uff08\u5982\u53d8\u91cf\u540d\u3001\u65b9\u6cd5\u540d\u3001\u7c7b\u540d\u7b49\uff09\u3002\u5b83\u901a\u8fc7\u00a0<code>#<\/code>\u00a0\u7b26\u53f7\u521b\u5efa\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>Symbol s = #someVariable; \/\/ \u8868\u793a\u6807\u8bc6\u7b26 'someVariable'<\/code><\/pre>\n\n\n\n<ul class=\"wp-block-list\">\n<li>\u53cd\u5c04\uff1a\u901a\u8fc7 <code>Symbol<\/code>\uff0c\u53ef\u4ee5\u5728\u8fd0\u884c\u65f6\u52a8\u6001\u5730\u8bbf\u95ee\u5bf9\u8c61\u7684\u5c5e\u6027\u6216\u65b9\u6cd5\uff0cFlutter\u4e2d\u88ab\u7981\u7528<\/li>\n\n\n\n<li>\u5143\u7f16\u7a0b\uff1a\u5728\u8fd0\u884c\u65f6\u52a8\u6001\u751f\u6210\u6216\u4fee\u6539\u4ee3\u7801<\/li>\n\n\n\n<li>\u907f\u514d\u786c\u7f16\u7801\u5b57\u7b26\u4e32\uff1a\u9700\u8981\u52a8\u6001\u8bbf\u95ee\u5c5e\u6027\u6216\u65b9\u6cd5\u65f6\uff0c\u7528 <code>Symbol<\/code> \u53ef\u4ee5\u907f\u514d\u786c\u7f16\u7801\u5b57\u7b26\u4e32\uff0c\u51cf\u5c11\u9519\u8bef<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">Symbol\u4f7f\u7528\u9891\u7387\u975e\u5e38\u4f4e\uff0c\u8fd9\u91cc\u4e0d\u518d\u8bf4\u4e86<\/p>\n\n\n\n<p class=\"has-text-align-center wp-block-paragraph\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-purple-color\">\u8bb0\u5f55<\/mark><\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u8bb0\u5f55\u662f\u4e00\u79cd\u533f\u540d\u3001\u4e0d\u53ef\u53d8\u3001\u805a\u5408\u7c7b\u578b\u3002\u50cf\u5176\u4ed6\u00a0<a href=\"https:\/\/dart.ac.cn\/language\/collections\">\u96c6\u5408\u7c7b\u578b<\/a>\u00a0\u4e00\u6837\uff0c\u5b83\u4eec\u5141\u8bb8\u4f60\u5c06\u591a\u4e2a\u5bf9\u8c61\u6253\u5305\u6210\u4e00\u4e2a\u5bf9\u8c61\u3002\u4e0e\u5176\u4ed6\u96c6\u5408\u7c7b\u578b\u4e0d\u540c\uff0c\u8bb0\u5f55\u662f\u56fa\u5b9a\u5927\u5c0f\u3001\u5f02\u6784\u4e14\u7c7b\u578b\u5316\u7684<\/p>\n\n\n\n<p class=\"has-luminous-vivid-amber-background-color has-background wp-block-paragraph\">\u4ec0\u4e48\u662f\u5f02\u6784\uff1a\u200b<strong>\u200b\u5f02\u6784\uff08Heterogeneous\uff09\u200b<\/strong>\u200b\u6307\u7684\u662f\u4e00\u4e2a\u6570\u636e\u7ed3\u6784\u6216\u96c6\u5408\u4e2d\u200b<strong>\u200b\u53ef\u4ee5\u5305\u542b\u4e0d\u540c\u7c7b\u578b\u7684\u6570\u636e\u5143\u7d20\u200b<\/strong>\u200b\u3002\u4e0e\u4e4b\u76f8\u5bf9\u7684\u662f\u200b<strong>\u200b\u540c\u6784\uff08Homogeneous\uff09\u200b<\/strong>\u200b\uff0c\u5373\u6240\u6709\u5143\u7d20\u7c7b\u578b\u76f8\u540c<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u8bb0\u5f55\u662f\u5b9e\u9645\u7684\u503c\uff1b\u4f60\u53ef\u4ee5\u5c06\u5b83\u4eec\u5b58\u50a8\u5728\u53d8\u91cf\u4e2d\uff0c\u5d4c\u5957\u5b83\u4eec\uff0c\u5728\u51fd\u6570\u4e4b\u95f4\u4f20\u9012\u5b83\u4eec\uff0c\u4ee5\u53ca\u5c06\u5b83\u4eec\u5b58\u50a8\u5728\u5217\u8868\u3001\u6620\u5c04\u548c\u96c6\u5408\u7b49\u6570\u636e\u7ed3\u6784\u4e2d<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong><mark style=\"background-color:rgba(0, 0, 0, 0)\" class=\"has-inline-color has-vivid-purple-color\"><em>\u8bb0\u5f55\u8868\u8fbe\u5f0f<\/em>\u00a0<\/mark><\/strong>\u662f\u7528\u9017\u53f7\u5206\u9694\u7684\u547d\u540d\u6216\u4f4d\u7f6e\u5b57\u6bb5\u5217\u8868\uff0c\u7528\u62ec\u53f7\u62ec\u8d77\u6765\uff0c\u8bed\u6cd5\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>#record\u53ea\u662fi\u4e00\u4e2a\u53d8\u91cf\u540d\uff0c\u8bb0\u5f55\u540d\u5b57\u53ef\u4ee5\u81ea\u5b9a\u4e49\uff0c\u4e0d\u4e00\u5b9a\u662frecord\nvar record = ('first', a: 2, b: true, 'last',100);\/\/\u5f02\u6784<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\"><em>\u8bb0\u5f55\u7c7b\u578b\u6ce8\u89e3<\/em>\u00a0\u662f\u7528\u9017\u53f7\u5206\u9694\u5e76\u7528\u62ec\u53f7\u62ec\u8d77\u6765\u7684\u7c7b\u578b\u5217\u8868\u3002\u660e\u786e\u6307\u5b9a\u8bb0\u5f55\u7684\u7ed3\u6784\u548c\u5b57\u6bb5\u7c7b\u578b(\u53ef\u5305\u542b\u4f4d\u7f6e\u5b57\u6bb5\u6216\u547d\u540d\u5b57\u6bb5)<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">1\u3001\u58f0\u660e\u4f4d\u7f6e\u5b57\u6bb5\u7684\u8bb0\u5f55\uff0c\u5e76\u8d4b\u503c\uff0c\u5982\u56fe\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"651\" height=\"135\" src=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/2-7.png\" alt=\"\" class=\"wp-image-18569\" srcset=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/2-7.png 651w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/2-7-300x62.png 300w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/2-7-600x124.png 600w\" sizes=\"auto, (max-width: 651px) 100vw, 651px\" \/><\/figure>\n\n\n\n<p class=\"has-luminous-vivid-amber-background-color has-background wp-block-paragraph\">\u6ce8\u610f\uff1a\u4f4d\u7f6e\u5b57\u6bb5\u5728\u7ed9\u8bb0\u5f55\u8d4b\u503c\u7684\u4f4d\u7f6e\u5fc5\u987b\u4e0e\u58f0\u660e\u65f6\u7684\u4e00\u81f4\uff0c\u6bd4\u5982\u58f0\u660e\u7684\u65f6\u5019\u662f(int,String)\uff0c\u90a3\u4e48\u8d4b\u503c\u4e0d\u80fd\u662f(String,int)<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">2\u3001\u58f0\u660e\u547d\u540d\u5b57\u6bb5\uff0c\u8d4b\u503c\u7684\u65f6\u5019\u4e0d\u53d7\u987a\u5e8f\u7684\u5f71\u54cd\uff0c\u56e0\u4e3a\u6839\u636e\u5b57\u6bb5\u540d\u8d4b\u503c\uff0c\u5982\u56fe\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"650\" height=\"138\" src=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/3-7.png\" alt=\"\" class=\"wp-image-18573\" srcset=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/3-7.png 650w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/3-7-300x64.png 300w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/3-7-600x127.png 600w\" sizes=\"auto, (max-width: 650px) 100vw, 650px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"648\" height=\"100\" src=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/4-7.png\" alt=\"\" class=\"wp-image-18574\" srcset=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/4-7.png 648w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/4-7-300x46.png 300w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/4-7-600x93.png 600w\" sizes=\"auto, (max-width: 648px) 100vw, 648px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">\u6ce8\u610f\uff1a\u4e0a\u9762\u7ed9record\u8d4b\u503c\u7684\u65f6\u5019\u6839\u636e\u5b57\u6bb5\u540d\u6765\u8d4b\u503c\uff0c\u5c31\u4e0d\u7528\u6309\u7167\u987a\u5e8f\u6765\u4e86<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">3\u3001\u53ef\u4ee5\u4f7f\u7528\u8bb0\u5f55\u7c7b\u578b\u6ce8\u89e3\u6765\u5b9a\u4e49\u8fd4\u56de\u7c7b\u578b\u548c\u53c2\u6570\u7c7b\u578b\uff0c\u5982\u56fe\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"658\" height=\"247\" src=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/4-6.png\" alt=\"\" class=\"wp-image-18561\" srcset=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/4-6.png 658w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/4-6-300x113.png 300w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/4-6-600x225.png 600w\" sizes=\"auto, (max-width: 658px) 100vw, 658px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"649\" height=\"81\" src=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/5-6.png\" alt=\"\" class=\"wp-image-18562\" srcset=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/5-6.png 649w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/5-6-300x37.png 300w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/5-6-600x75.png 600w\" sizes=\"auto, (max-width: 649px) 100vw, 649px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">4\u3001\u8bb0\u5f55\u5b57\u6bb5\u53ef\u901a\u8fc7\u5185\u7f6e\u7684getter\u6765\u8bbf\u95ee\uff0c\u56e0\u4e3a\u8bb0\u5f55\u4e0d\u53ef\u4fee\u6539\uff0c\u56e0\u4e3a\u6ca1\u6709setter\uff0c\u5982\u56fe\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"651\" height=\"150\" src=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/6-5.png\" alt=\"\" class=\"wp-image-18564\" srcset=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/6-5.png 651w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/6-5-300x69.png 300w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/6-5-600x138.png 600w\" sizes=\"auto, (max-width: 651px) 100vw, 651px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"649\" height=\"118\" src=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/7-7.png\" alt=\"\" class=\"wp-image-18565\" srcset=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/7-7.png 649w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/7-7-300x55.png 300w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/7-7-600x109.png 600w\" sizes=\"auto, (max-width: 649px) 100vw, 649px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">\u5982\u679ca:10\u5728\u524d\u9762\uff0c\u53d6\u540e\u9762\u5b57\u6bb5\u4e5f\u662f\u4ece$1\u5f00\u59cb\uff0c\u5982\u56fe\uff1a<\/p>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"663\" height=\"153\" src=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/5-7.png\" alt=\"\" class=\"wp-image-18576\" srcset=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/5-7.png 663w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/5-7-300x69.png 300w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/5-7-600x138.png 600w\" sizes=\"auto, (max-width: 663px) 100vw, 663px\" \/><\/figure>\n\n\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"653\" height=\"120\" src=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/6-6.png\" alt=\"\" class=\"wp-image-18578\" srcset=\"https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/6-6.png 653w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/6-6-300x55.png 300w, https:\/\/blog.ywdevops.cn\/wp-content\/uploads\/2025\/07\/6-6-600x110.png 600w\" sizes=\"auto, (max-width: 653px) 100vw, 653px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">5\u3001\u5982\u679c\u4e24\u4e2a\u8bb0\u5f55\u5177\u6709\u76f8\u540c\u7684\u5b57\u6bb5\u96c6\uff0c\u5e76\u4e14\u5176\u76f8\u5e94\u5b57\u6bb5\u5177\u6709\u76f8\u540c\u7684\u503c\uff0c\u5219\u5b83\u4eec\u76f8\u7b49\uff0c\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>(int x, int y, int z) point = (1, 2, 3);\n(int r, int g, int b) color = (1, 2, 3);\nprint(point == color); \/\/ Prints 'true'<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>Dart \u8bed\u8a00\u5bf9\u4ee5\u4e0b\u7c7b\u578b\u6709\u7279\u6b8a\u652f\u6301\uff1a \u56e0\u4e3a Dart \u4e2d\u7684\u6bcf\u4e2a\u53d8\u91cf\u90fd\u6307\u5411\u4e00\u4e2a\u5bf9\u8c61&#8211;&gt;\u4e00\u4e2a\u7c7b\u7684 [&hellip;]<\/p>\n","protected":false},"author":3,"featured_media":18515,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[158],"tags":[],"class_list":["post-18513","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-dart"],"blocksy_meta":{"styles_descriptor":{"styles":{"desktop":"","tablet":"","mobile":""},"google_fonts":[],"version":8}},"_links":{"self":[{"href":"https:\/\/blog.ywdevops.cn\/index.php\/wp-json\/wp\/v2\/posts\/18513","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.ywdevops.cn\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.ywdevops.cn\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.ywdevops.cn\/index.php\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.ywdevops.cn\/index.php\/wp-json\/wp\/v2\/comments?post=18513"}],"version-history":[{"count":46,"href":"https:\/\/blog.ywdevops.cn\/index.php\/wp-json\/wp\/v2\/posts\/18513\/revisions"}],"predecessor-version":[{"id":18550,"href":"https:\/\/blog.ywdevops.cn\/index.php\/wp-json\/wp\/v2\/posts\/18513\/revisions\/18550"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blog.ywdevops.cn\/index.php\/wp-json\/wp\/v2\/media\/18515"}],"wp:attachment":[{"href":"https:\/\/blog.ywdevops.cn\/index.php\/wp-json\/wp\/v2\/media?parent=18513"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.ywdevops.cn\/index.php\/wp-json\/wp\/v2\/categories?post=18513"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.ywdevops.cn\/index.php\/wp-json\/wp\/v2\/tags?post=18513"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}