预定义常量
 下列常量由此扩展定义,且仅在此扩展编译入 PHP 或在运行时动态载入时可用。
 
  
   - 
    
MB_OVERLOAD_MAIL 
    (int)
    
   - 
    
     自 PHP 8.0.0 起已删除。
    
   
 
  
  
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MB_OVERLOAD_STRING 
    (int)
    
   - 
    
     自 PHP 8.0.0 起已删除。
    
   
 
  
  
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MB_OVERLOAD_REGEX 
    (int)
    
   - 
    
     自 PHP 8.0.0 起已删除。
    
   
 
  
  
   - 
    
MB_CASE_UPPER 
    (int)
    
   - 
    
     Performs a full upper-case folding.
     This may change the length of the string.
     This is the mode used by mb_strtoupper().
    
   
 
  
  
   - 
    
MB_CASE_LOWER 
    (int)
    
   - 
    
     Performs a full lower-case folding.
     This may change the length of the string.
     This is the mode used by mb_strtolower().
    
   
 
  
  
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MB_CASE_TITLE 
    (int)
    
   - 
    
     Performs a full title-case conversion based on the Cased and CaseIgnorable
     derived Unicode properties.
     In particular this improves handling of quotes and apostrophes.
     This may change the length of the string.
    
   
 
  
  
   - 
    
MB_CASE_FOLD 
    (int)
    
   - 
    
     Performs a full case fold conversion which removes case distinctions
     present in the string.
     This is used for caseless matching.
     This may change the length of the string.
     Available since PHP 7.3.
    
   
 
  
  
   - 
    
MB_CASE_LOWER_SIMPLE 
    (int)
    
   - 
    
     Performs a simple lower-case fold conversion.
     This does not change the length of the string.
     Available as of PHP 7.3.
    
   
 
  
  
   - 
    
MB_CASE_UPPER_SIMPLE 
    (int)
    
   - 
    
     Performs simple upper-case fold conversion.
     This does not change the length of the string.
     Available as of PHP 7.3.
    
   
 
  
  
   - 
    
MB_CASE_TITLE_SIMPLE 
    (int)
    
   - 
    
     Performs simple title-case fold conversion.
     This does not change the length of the string.
     Available as of PHP 7.3.
    
   
 
  
  
   - 
    
MB_CASE_FOLD_SIMPLE 
    (int)
    
   - 
    
     Performs a simple case fold conversion which removes case distinctions
     present in the string.
     This is used for caseless matching.
     This does not change the length of the string.
     Used by case-insensitive operations internally by the MBString extension.
     Available as of PHP 7.3.
    
   
 
  
  
   - 
    
MB_ONIGURUMA_VERSION 
    (string)
    
   - 
    
     Oniguruma 版本,例如 
6.9.4。自 PHP 7.4 起可用。