意想不到的(

开括号通常跟在if/foreach/for/array/list这样的语言结构之后，或者开始一个算术表达式。它们在“strings”后，previous()，单独的$和一些典型的声明上下文中都是语法错误的。

Function declaration parameters A rarer occurrence for this error is trying to use expressions as default function parameters. This is not supported, even in PHP7: function header_fallback($value, $expires = time() + 90000) { Parameters in a function declaration can only be literal values or constant expressions. Unlike for function invocations, where you can freely use whatever(1+something()*2), etc. Class property defaults Same thing for class member declarations, where only literal/constant values are allowed, not expressions: class xyz { ⇓ var $default = get_config("xyz_default"); Put such things in the constructor. See also Why don't PHP attributes allow functions? Again note that PHP 7 only allows var $xy = 1 + 2 +3; constant expressions there. JavaScript syntax in PHP Using JavaScript or jQuery syntax won't work in PHP for obvious reasons: <?php ⇓ print $(document).text(); When this happens, it usually indicates an unterminated preceding string; and literal <script> sections leaking into PHP code context. isset(()), empty, key, next, current Both isset() and empty() are language built-ins, not functions. They need to access a variable directly. If you inadvertently add a pair of parentheses too much, then you'd create an expression however: ⇓ if (isset(($_GET["id"]))) { The same applies to any language construct that requires implicit variable name access. These built-ins are part of the language grammar, therefore don't permit decorative extra parentheses. User-level functions that require a variable reference -but get an expression result passed- lead to runtime errors instead.

意想不到的)

Absent function parameter You cannot have stray commas last in a function call. PHP expects a value there and thusly complains about an early closing ) parenthesis. ⇓ callfunc(1, 2, ); A trailing comma is only allowed in array() or list() constructs. Unfinished expressions If you forget something in an arithmetic expression, then the parser gives up. Because how should it possibly interpret that: ⇓ $var = 2 * (1 + ); And if you forgot the closing ) even, then you'd get a complaint about the unexpected semicolon instead. Foreach as constant For forgotten variable $ prefixes in control statements you will see: ↓ ⇓ foreach ($array as wrong) { PHP here sometimes tells you it expected a :: instead. Because a class::$variable could have satisfied the expected $variable expression..

意想不到的{

花括号{和}括起代码块。关于它们的语法错误通常表示一些不正确的嵌套。

Unmatched subexpressions in an if Most commonly unbalanced ( and ) are the cause if the parser complains about the opening curly { appearing too early. A simple example: ⇓ if (($x == $y) && (2 == true) { Count your parentheses or use an IDE which helps with that. Also don't write code without any spaces. Readability counts. { and } in expression context You can't use curly braces in expressions. If you confuse parentheses and curlys, it won't comply to the language grammar: ⇓ $var = 5 * {7 + $x}; There are a few exceptions for identifier construction, such as local scope variable ${references}. Variable variables or curly var expressions This is pretty rare. But you might also get { and } parser complaints for complex variable expressions: ⇓ print "Hello {$world[2{]} !"; Though there's a higher likelihood for an unexpected } in such contexts.

意想不到的}

当出现“意外}”错误时，您多半过早地关闭了代码块。

Last statement in a code block It can happen for any unterminated expression. And if the last line in a function/code block lacks a trailing ; semicolon: function whatever() { doStuff() } ⇧ Here the parser can't tell if you perhaps still wanted to add + 25; to the function result or something else. Invalid block nesting / Forgotten { You'll sometimes see this parser error when a code block was } closed too early, or you forgot an opening { even: function doStuff() { if (true) ⇦ print "yes"; } } ⇧ In above snippet the if didn't have an opening { curly brace. Thus the closing } one below became redundant. And therefore the next closing }, which was intended for the function, was not associable to the original opening { curly brace. Such errors are even harder to find without proper code indentation. Use an IDE and bracket matching.

意料之外的，期待的

需要条件/声明标头和代码块的语言构造将触发此错误。

参数列表 例如，不允许错误声明没有参数列表的函数: ⇓ 函数whatever { ｝ 控制语句条件 你也不能无条件地有一个如果。 ⇓ 如果{ ｝ 这显然说不通。对于常见的疑点，for/foreach, while/do等等，也是如此。 如果您遇到了这种特殊的错误，您绝对应该查找一些手册示例。

意外的T_CONSTANT_ENCAPSED_STRING意外的t_encapsed_and_空白

T_CONSTANT_ENCAPSED_STRING和T_ENCAPSED_AND_WHITESPACE是指带引号的“字符串”字面量。

它们在不同的上下文中使用，但语法问题非常相似。t_encaged…警告出现在双引号的字符串上下文中，而T_CONSTANT…字符串经常在普通PHP表达式或语句中出错。

Incorrect variable interpolation And it comes up most frequently for incorrect PHP variable interpolation: ⇓ ⇓ echo "Here comes a $wrong['array'] access"; Quoting arrays keys is a must in PHP context. But in double quoted strings (or HEREDOCs) this is a mistake. The parser complains about the contained single quoted 'string', because it usually expects a literal identifier / key there. More precisely it's valid to use PHP2-style simple syntax within double quotes for array references: echo "This is only $valid[here] ..."; Nested arrays or deeper object references however require the complex curly string expression syntax: echo "Use {$array['as_usual']} with curly syntax."; If unsure, this is commonly safer to use. It's often even considered more readable. And better IDEs actually use distinct syntax colorization for that. Missing concatenation If a string follows an expression, but lacks a concatenation or other operator, then you'll see PHP complain about the string literal: ⇓ print "Hello " . WORLD " !"; While it's obvious to you and me, PHP just can't guess that the string was meant to be appended there. Confusing string quote enclosures The same syntax error occurs when confounding string delimiters. A string started by a single ' or double " quote also ends with the same. ⇓ print "<a href="' . $link . '">click here</a>"; ⌞⎽⎽⎽⎽⎽⎽⎽⎽⌟⌞⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⌟⌞⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⎽⌟ That example started with double quotes. But double quotes were also destined for the HTML attributes. The intended concatenation operator within however became interpreted as part of a second string in single quotes. Tip: Set your editor/IDE to use slightly distinct colorization for single and double quoted strings. (It also helps with application logic to prefer e.g. double quoted strings for textual output, and single quoted strings only for constant-like values.) This is a good example where you shouldn't break out of double quotes in the first place. Instead just use proper \" escapes for the HTML attributes´ quotes: print "<a href=\"{$link}\">click here</a>"; While this can also lead to syntax confusion, all better IDEs/editors again help by colorizing the escaped quotes differently. Missing opening quote Equivalently are forgotten opening "/' quotes a recipe for parser errors: ⇓ make_url(login', 'open'); Here the ', ' would become a string literal after a bareword, when obviously login was meant to be a string parameter. Array lists If you miss a , comma in an array creation block, the parser will see two consecutive strings: array( ⇓ "key" => "value" "next" => "....", ); Note that the last line may always contain an extra comma, but overlooking one in between is unforgivable. Which is hard to discover without syntax highlighting. Function parameter lists The same thing for function calls: ⇓ myfunc(123, "text", "and" "more") Runaway strings A common variation are quite simply forgotten string terminators: ⇓ mysql_evil("SELECT * FROM stuffs); print "'ok'"; ⇑ Here PHP complains about two string literals directly following each other. But the real cause is the unclosed previous string of course. HEREDOC indentation Prior PHP 7.3, the heredoc string end delimiter can't be prefixed with spaces: print <<< HTML <link..> HTML; ⇑ Solution: upgrade PHP or find a better hoster.

另请参阅

PHP中关联数组的插值(双引号字符串) 语法错误，意外的T_CONSTANT_ENCAPSED_STRING 语法错误，PHP中意外的T_CONSTANT_ENCAPSED_STRING SQL查询中出现意外的T_CONSTANT_ENCAPSED_STRING错误

意想不到的(

开括号通常跟在if/foreach/for/array/list这样的语言结构之后，或者开始一个算术表达式。它们在“strings”后，previous()，单独的$和一些典型的声明上下文中都是语法错误的。

Function declaration parameters A rarer occurrence for this error is trying to use expressions as default function parameters. This is not supported, even in PHP7: function header_fallback($value, $expires = time() + 90000) { Parameters in a function declaration can only be literal values or constant expressions. Unlike for function invocations, where you can freely use whatever(1+something()*2), etc. Class property defaults Same thing for class member declarations, where only literal/constant values are allowed, not expressions: class xyz { ⇓ var $default = get_config("xyz_default"); Put such things in the constructor. See also Why don't PHP attributes allow functions? Again note that PHP 7 only allows var $xy = 1 + 2 +3; constant expressions there. JavaScript syntax in PHP Using JavaScript or jQuery syntax won't work in PHP for obvious reasons: <?php ⇓ print $(document).text(); When this happens, it usually indicates an unterminated preceding string; and literal <script> sections leaking into PHP code context. isset(()), empty, key, next, current Both isset() and empty() are language built-ins, not functions. They need to access a variable directly. If you inadvertently add a pair of parentheses too much, then you'd create an expression however: ⇓ if (isset(($_GET["id"]))) { The same applies to any language construct that requires implicit variable name access. These built-ins are part of the language grammar, therefore don't permit decorative extra parentheses. User-level functions that require a variable reference -but get an expression result passed- lead to runtime errors instead.

意想不到的)

Absent function parameter You cannot have stray commas last in a function call. PHP expects a value there and thusly complains about an early closing ) parenthesis. ⇓ callfunc(1, 2, ); A trailing comma is only allowed in array() or list() constructs. Unfinished expressions If you forget something in an arithmetic expression, then the parser gives up. Because how should it possibly interpret that: ⇓ $var = 2 * (1 + ); And if you forgot the closing ) even, then you'd get a complaint about the unexpected semicolon instead. Foreach as constant For forgotten variable $ prefixes in control statements you will see: ↓ ⇓ foreach ($array as wrong) { PHP here sometimes tells you it expected a :: instead. Because a class::$variable could have satisfied the expected $variable expression..

意想不到的{

花括号{和}括起代码块。关于它们的语法错误通常表示一些不正确的嵌套。

Unmatched subexpressions in an if Most commonly unbalanced ( and ) are the cause if the parser complains about the opening curly { appearing too early. A simple example: ⇓ if (($x == $y) && (2 == true) { Count your parentheses or use an IDE which helps with that. Also don't write code without any spaces. Readability counts. { and } in expression context You can't use curly braces in expressions. If you confuse parentheses and curlys, it won't comply to the language grammar: ⇓ $var = 5 * {7 + $x}; There are a few exceptions for identifier construction, such as local scope variable ${references}. Variable variables or curly var expressions This is pretty rare. But you might also get { and } parser complaints for complex variable expressions: ⇓ print "Hello {$world[2{]} !"; Though there's a higher likelihood for an unexpected } in such contexts.

意想不到的}

当出现“意外}”错误时，您多半过早地关闭了代码块。

Last statement in a code block It can happen for any unterminated expression. And if the last line in a function/code block lacks a trailing ; semicolon: function whatever() { doStuff() } ⇧ Here the parser can't tell if you perhaps still wanted to add + 25; to the function result or something else. Invalid block nesting / Forgotten { You'll sometimes see this parser error when a code block was } closed too early, or you forgot an opening { even: function doStuff() { if (true) ⇦ print "yes"; } } ⇧ In above snippet the if didn't have an opening { curly brace. Thus the closing } one below became redundant. And therefore the next closing }, which was intended for the function, was not associable to the original opening { curly brace. Such errors are even harder to find without proper code indentation. Use an IDE and bracket matching.

意料之外的，期待的

需要条件/声明标头和代码块的语言构造将触发此错误。

参数列表 例如，不允许错误声明没有参数列表的函数: ⇓ 函数whatever { ｝ 控制语句条件 你也不能无条件地有一个如果。 ⇓ 如果{ ｝ 这显然说不通。对于常见的疑点，for/foreach, while/do等等，也是如此。 如果您遇到了这种特殊的错误，您绝对应该查找一些手册示例。

我认为这个话题讨论得太多了/太复杂了。使用IDE是完全避免任何语法错误的方法。我甚至会说，在没有IDE的情况下工作是不专业的。为什么?因为现代ide会在输入每个字符后检查语法。当您编写代码时，整行代码都变成红色，并且有一个很大的警告通知显示语法错误的确切类型和确切位置，那么绝对没有必要搜索其他解决方案。

使用语法检查IDE意味着:

您将(有效地)再也不会遇到语法错误，因为您在输入时就能看到它们。认真对待。

具有语法检查功能的优秀ide(它们都适用于Linux、Windows和Mac):

NetBeans(免费) PHPStorm [$199 USD] Eclipse与PHP插件[免费] Sublime [$80 USD](主要是一个文本编辑器，但可扩展的插件，如PHP语法分析器)

意想不到的T_STRING

T_STRING有点用词不当。它不引用引用的“字符串”。这意味着遇到了原始标识符。这可以是空白的单词、剩余的CONSTANT或函数名、被遗忘的不带引号的字符串或任何纯文本。

Misquoted strings This syntax error is most common for misquoted string values however. Any unescaped and stray " or ' quote will form an invalid expression: ⇓ ⇓ echo "<a href="http://example.com">click here</a>"; Syntax highlighting will make such mistakes super obvious. It's important to remember to use backslashes for escaping \" double quotes, or \' single quotes - depending on which was used as string enclosure. For convenience you should prefer outer single quotes when outputting plain HTML with double quotes within. Use double quoted strings if you want to interpolate variables, but then watch out for escaping literal " double quotes. For lengthier output, prefer multiple echo/print lines instead of escaping in and out. Better yet consider a HEREDOC section. Another example is using PHP entry inside HTML code generated with PHP: $text = '<div>some text with <?php echo 'some php entry' ?></div>' This happens if $text is large with many lines and developer does not see the whole PHP variable value and focus on the piece of code forgetting about its source. Example is here See also What is the difference between single-quoted and double-quoted strings in PHP?. Unclosed strings If you miss a closing " then a syntax error typically materializes later. An unterminated string will often consume a bit of code until the next intended string value: ⇓ echo "Some text", $a_variable, "and some runaway string ; success("finished"); ⇯ It's not just literal T_STRINGs which the parser may protest then. Another frequent variation is an Unexpected '>' for unquoted literal HTML. Non-programming string quotes If you copy and paste code from a blog or website, you sometimes end up with invalid code. Typographic quotes aren't what PHP expects: $text = ’Something something..’ + ”these ain't quotes”; Typographic/smart quotes are Unicode symbols. PHP treats them as part of adjoining alphanumeric text. For example ”these is interpreted as a constant identifier. But any following text literal is then seen as a bareword/T_STRING by the parser. The missing semicolon; again If you have an unterminated expression in previous lines, then any following statement or language construct gets seen as raw identifier: ⇓ func1() function2(); PHP just can't know if you meant to run two functions after another, or if you meant to multiply their results, add them, compare them, or only run one || or the other. Short open tags and <?xml headers in PHP scripts This is rather uncommon. But if short_open_tags are enabled, then you can't begin your PHP scripts with an XML declaration: ⇓ <?xml version="1.0"?> PHP will see the <? and reclaim it for itself. It won't understand what the stray xml was meant for. It'll get interpreted as constant. But the version will be seen as another literal/constant. And since the parser can't make sense of two subsequent literals/values without an expression operator in between, that'll be a parser failure. Invisible Unicode characters A most hideous cause for syntax errors are Unicode symbols, such as the non-breaking space. PHP allows Unicode characters as identifier names. If you get a T_STRING parser complaint for wholly unsuspicious code like: <?php print 123; You need to break out another text editor. Or an hexeditor even. What looks like plain spaces and newlines here, may contain invisible constants. Java-based IDEs are sometimes oblivious to an UTF-8 BOM mangled within, zero-width spaces, paragraph separators, etc. Try to reedit everything, remove whitespace and add normal spaces back in. You can narrow it down with with adding redundant ; statement separators at each line start: <?php ;print 123; The extra ; semicolon here will convert the preceding invisible character into an undefined constant reference (expression as statement). Which in return makes PHP produce a helpful notice. The `$` sign missing in front of variable names Variables in PHP are represented by a dollar sign followed by the name of the variable. The dollar sign ($) is a sigil that marks the identifier as a name of a variable. Without this sigil, the identifier could be a language keyword or a constant. This is a common error when the PHP code was "translated" from code written in another language (C, Java, JavaScript, etc.). In such cases, a declaration of the variable type (when the original code was written in a language that uses typed variables) could also sneak out and produce this error. Escaped Quotation marks If you use \ in a string, it has a special meaning. This is called an "Escape Character" and normally tells the parser to take the next character literally. Example: echo 'Jim said \'Hello\''; will print Jim said 'hello' If you escape the closing quote of a string, the closing quote will be taken literally and not as intended, i.e. as a printable quote as part of the string and not close the string. This will show as a parse error commonly after you open the next string or at the end of the script. Very common error when specifiying paths in Windows: "C:\xampp\htdocs\" is wrong. You need "C:\\xampp\\htdocs\\". Typed properties You need PHP ≥7.4 to use property typing such as: public stdClass $obj;

对于VS Code的新手，如果你看到语法错误，检查你是否保存了文件。如果你有一个错误的语法，保存文件，然后在不保存的情况下修复语法，VS Code会继续显示错误。只有保存文件后，错误信息才会消失。