PHP: 预定义常量 - Manual

传递给 json_encode() 函数的对象或数组包含了递归引用，导致无法被编码。如果打开了 JSON_PARTIAL_OUTPUT_ON_ERROR 选项，则牵涉到递归引用的数据会转换成 null 后返回。传递了不支持的数据类型给 json_encode() 函数，比如 resource 。如果打开了 JSON_PARTIAL_OUTPUT_ON_ERROR 选项，则对于不支持的数据类型，会转换成 null 后返回。 A key starting with \u0000 character was in the string passed to json_decode() when decoding a JSON object into a PHP object. The line terminators are kept unescaped when JSON_UNESCAPED_UNICODE is supplied. It uses the same behaviour as it was before PHP 7.1 without this constant. Available since PHP 7.1.0. 如果发生错误则会抛出 JsonException ，而不是通过 json_last_error() 和 json_last_error_msg() 检索设置到全局的错误状态。 JSON_PARTIAL_OUTPUT_ON_ERROR 优先于 JSON_THROW_ON_ERROR 。自 PHP 7.3.0 起生效。 majid4466 at gmail dot com ¶

8 years ago


    
     To get a really clean json string use these three constants like so:
     

     

     
      <?php
      

      $array
     
     
      = [
     
     
      '€'
     
     
      ,
     
     
      '
      
       http://example.com/some/cool/page
      
      '
     
     
      ,
     
     
      '337'
     
     
      ];
      

     
     
      $bad
     
     
      =
     
     
      json_encode
     
     
      (
     
     
      $array
     
     
      );
      

     
     
      $good
     
     
      =
     
     
      json_encode
     
     
      (
     
     
      $array
     
     
      ,
     
     
      JSON_UNESCAPED_UNICODE
     
     
      |
     
     
      JSON_UNESCAPED_SLASHES
     
     
      |
     
     
      JSON_NUMERIC_CHECK
     
     
      );
      

      

     
     
      // $bad would be  ["\u20ac","http:\/\/example.com\/some\/cool\/page","337"]
      

      // $good would be ["€","
      
       http://example.com/some/cool/page
      
      ",337]
      

     
     
      ?>

Yzmir Ramirez ¶

10 years ago


    
     If you curious of the numeric values of the constants, as of JSON 1.2.1, the constants have the following values (not that you should use the numbers directly):
     

     

     JSON_HEX_TAG => 1
     

     JSON_HEX_AMP => 2
     

     JSON_HEX_APOS => 4
     

     JSON_HEX_QUOT => 8
     

     JSON_FORCE_OBJECT => 16
     

     JSON_NUMERIC_CHECK => 32
     

     JSON_UNESCAPED_SLASHES => 64
     

     JSON_PRETTY_PRINT => 128
     

     JSON_UNESCAPED_UNICODE => 256
     

     

     JSON_ERROR_DEPTH => 1
     

     JSON_ERROR_STATE_MISMATCH => 2
     

     JSON_ERROR_CTRL_CHAR => 3
     

     

     JSON_ERROR_SYNTAX => 4
     

     

     JSON_ERROR_UTF8 => 5
     

     JSON_OBJECT_AS_ARRAY => 1
     

     

     JSON_BIGINT_AS_STRING => 2

nikospapoutsis ¶

2 years ago


    
     Be EXTREMELY cautious when using the code majid4466 at gmail dot com provided, or JSON_NUMERIC_CHECK in general.
     

     

     For example, in php 7.4 and 8.1 with precision: 14 and serialize_precision: -1 we get:
     

     

     
      <?php
      

      $array
     
     
      = [
     
     
      '€'
     
     
      ,
     
     
      55.6666666666666666
     
     
      ,
     
     
      '
      
       http://example.com/some/cool/page
      
      '
     
     
      ,
     
     
      '000337'
     
     
      ,
     
     
      '55.6666666666666666'
     
     
      ];
      

      echo
     
     
      $case1
     
     
      =
     
     
      json_encode
     
     
      (
     
     
      $array
     
     
      );
      

      echo
     
     
      $case2
     
     
      =
     
     
      json_encode
     
     
      (
     
     
      $array
     
     
      ,
     
     
      JSON_UNESCAPED_UNICODE
     
     
      |
     
     
      JSON_UNESCAPED_SLASHES
     
     
      );
      

      echo
     
     
      $case3
     
     
      =
     
     
      json_encode
     
     
      (
     
     
      $array
     
     
      ,
     
     
      JSON_UNESCAPED_UNICODE
     
     
      |
     
     
      JSON_UNESCAPED_SLASHES
     
     
      |
     
     
      JSON_NUMERIC_CHECK
     
     
      );
      

      

      [
     
     
      "\u20ac"
     
     
      ,
     
     
      55.666666666666664
     
     
      ,
     
     
      "http:\/\/example.com\/some\/cool\/page"
     
     
      ,
     
     
      "000337"
     
     
      ,
     
     
      "55.6666666666666666"
     
     
      ]
      

     
     
      // in $case1, both euro sign and the url change but we also lost a digit in our unquoted float (due to precision)
      

      

     
     
      [
     
     
      "€"
     
     
      ,
     
     
      55.666666666666664
     
     
      ,
     
     
      "
      
       http://example.com/some/cool/page
      
      "
     
     
      ,
     
     
      "000337"
     
     
      ,
     
     
      "55.6666666666666666"
     
     
      ]
      

     
     
      // in $case2, both euro sign and the url stay exactly the same but we still lost a digit in our unquoted float (due to precision)
      

      

     
     
      [
     
     
      "€"
     
     
      ,
     
     
      55.666666666666664
     
     
      ,
     
     
      "
      
       http://example.com/some/cool/page
      
      "
     
     
      ,
     
     
      337
     
     
      ,
     
     
      55.666666666666664
     
     
      ]
      

     
     
      // in $case3, we once again keep euro sign and the url intact but this time not only our unquoted float lost a digit
      

      // but the same happened to our quoted float and the number/string lost its leading zeros too
      

      

     
     
      Also
     
     
      ,
     
     
      note that in php 5.x you will probably get some different but equally wrong results
     
     
      as default
     
     
      values may be different
     
     
      and
     
     
      some functions have changed internally
     
     
      as
     
     
      well
     
     
      .

ASchmidt at Anamera dot net ¶

6 years ago


    
     In a multi-level array, JSON_FORCE_OBJECT will encode ALL nested numeric arrays as objects.
     

     

     If your concern was ONLY the first-level array (e.g., to make it suitable as a MySQL JSON column), you could just cast your first-level array to object, e.g.:
     

     

     
      <?php
      

      $json
     
     
      =
     
     
      json_encode
     
     
      ( (object)
     
     
      $array
     
     
      ,
     
     
      JSON_PRESERVE_ZERO_FRACTION
     
     
      +
     
     
      JSON_UNESCAPED_UNICODE
     
     
      );
      

     
     
      ?>
      

     
     

     Or, if you have large arrays and are concerned about the overhead of object casting, you could append a "null" value beyond the size of the array, which will force the array to become associative:
     

     

     
      <?php
      

      $beyond
     
     
      =
     
     
      count
     
     
      (
     
     
      $array
     
     
      ) +
     
     
      1
     
     
      ;
      

      if ( !
     
     
      array_key_exists
     
     
      (
     
     
      $beyond
     
     
      ,
     
     
      $array
     
     
      ) )
      

     
     
      $array
     
     
      [
     
     
      $beyond
     
     
      ] =
     
     
      NULL
     
     
      ;
      

     
     
      $json
     
     
      =
     
     
      json_encode
     
     
      (
     
     
      $array
     
     
      ,
     
     
      JSON_PRESERVE_ZERO_FRACTION
     
     
      +
     
     
      JSON_UNESCAPED_UNICODE
     
     
      );
      

     
     
      ?>
      

     
     

     Of course, your later code has to treat an element with a "NULL" value the same as "!isset()", if it iterates the array.

eduard dot amoros dot wahl at gmail dot com ¶

1 month ago


    
     Warning about JSON_NUMERIC_CHECK and scientific notation.
     

     

     JSON_NUMERIC_CHECK will remove scientific notation. Thus,
     

     json_encode(['scientificNumber' => '1e-4'], JSON_NUMERIC_CHECK);
     

     will return {"scientificNumber":0.0001}
     

     

     You have to account for this, as it may defeat the whole purpose of scientific notation.

Anonymous ¶

6 years ago


    
     flags JSON_NUMERIC_CHECK and JSON_PRESERVE_ZERO_FRACTION are broken in php 7+ — json_encode((float)8.8) returns "8.8000000000000007", and json_encode((float)8.8, JSON_NUMERIC_CHECK) and json_encode((float)8.8, JSON_PRESERVE_ZERO_FRACTION) return "8.8000000000000007" too.
     

     

     the only way to fix this is setting "serialize_precision = -1" in php.ini

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