QStringRef 类提供的瘦包裹器围绕 QString 子字符串。 更多...
QStringRef 类提供的瘦包裹器围绕 QString 子字符串。
QStringRef provides a read-only subset of the QString API.
A string reference explicitly references a portion of a string () with a given size (), starting at a specific position (). Calling toString () returns a copy of the data as a real QString 实例。
This class is designed to improve the performance of substring handling when manipulating substrings obtained from existing QString instances. QStringRef avoids the memory allocation and reference counting overhead of a standard QString by simply referencing a part of the original string. This can prove to be advantageous in low level code, such as that used in a parser, at the expense of potentially more complex code.
For most users, there are no semantic benefits to using QStringRef instead of QString since QStringRef requires attention to be paid to memory management issues, potentially making code more complex to write and maintain.
警告： A QStringRef is only valid as long as the referenced string exists. If the original string is deleted, the string reference points to an invalid memory location.
We suggest that you only use this class in stable code where profiling has clearly identified that performance improvements can be made by replacing standard string operations with the optimized substring handling provided by this class.
Constructs an empty string reference.
Constructs a string reference to the range of characters in the given string specified by the starting position and length in characters.
警告： This function exists to improve performance as much as possible, and performs no bounds checking. For program correctness, position and length must describe a valid substring of string .
This means that the starting position must be positive or 0 and smaller than string 's length, and length must be positive or 0 but smaller than the string's length minus the starting position ; i.e, 0 <= position < string-> length () and 0 <= length <= string-> length () - position must both be satisfied.
Constructs a string reference to the given string .
构造副本为 other string reference.
Appends the string reference to string , and returns a new reference to the combined string data.
Returns the character at the given index position 在 string reference.
position must be a valid index position in the string (i.e., 0 <= position < size ()).
Clears the contents of the string reference by making it null and empty.
另请参阅 isEmpty () and isNull ().
Compares the string s1 with the string s2 and returns an integer less than, equal to, or greater than zero if s1 is less than, equal to, or greater than s2 .
若 cs is Qt.CaseSensitive ， comparison is case sensitive; otherwise the comparison is case insensitive.
该函数在 Qt 4.5 引入。
这是重载函数。
Compares the string s1 with the string s2 and returns an integer less than, equal to, or greater than zero if s1 is less than, equal to, or greater than s2 .
若 cs is Qt.CaseSensitive ， comparison is case sensitive; otherwise the comparison is case insensitive.
该函数在 Qt 4.5 引入。
这是重载函数。
Compares the string s1 with the string s2 and returns an integer less than, equal to, or greater than zero if s1 is less than, equal to, or greater than s2 .
若 cs is Qt.CaseSensitive ， comparison is case sensitive; otherwise the comparison is case insensitive.
该函数在 Qt 4.5 引入。
这是重载函数。
Compares this string with the other string and returns an integer less than, equal to, or greater than zero if this string is less than, equal to, or greater than the other string.
若 cs is Qt.CaseSensitive ， comparison is case sensitive; otherwise the comparison is case insensitive.
相当于 compare(*this, other, cs) .
该函数在 Qt 4.5 引入。
另请参阅 QString.compare ().
这是重载函数。
Compares this string with the other string and returns an integer less than, equal to, or greater than zero if this string is less than, equal to, or greater than the other string.
若 cs is Qt.CaseSensitive ， comparison is case sensitive; otherwise the comparison is case insensitive.
相当于 compare(*this, other, cs) .
该函数在 Qt 4.5 引入。
另请参阅 QString.compare ().
这是重载函数。
Compares this string with the other string and returns an integer less than, equal to, or greater than zero if this string is less than, equal to, or greater than the other string.
若 cs is Qt.CaseSensitive ， comparison is case sensitive; otherwise the comparison is case insensitive.
相当于 compare(*this, other, cs) .
该函数在 Qt 4.5 引入。
另请参阅 QString.compare ().
如同 unicode ().
Returns true if this string reference contains an occurrence of the string str ；否则返回 false。
若 cs is Qt.CaseSensitive (default), the search is case sensitive; otherwise the search is case insensitive.
该函数在 Qt 4.8 引入。
此函数重载 contains ().
Returns true if this string contains an occurrence of the character ch ；否则返回 false。
若 cs is Qt.CaseSensitive (default), the search is case sensitive; otherwise the search is case insensitive.
该函数在 Qt 4.8 引入。
此函数重载 contains ().
Returns true if this string reference contains an occurrence of the string reference str ；否则返回 false。
若 cs is Qt.CaseSensitive (default), the search is case sensitive; otherwise the search is case insensitive.
该函数在 Qt 4.8 引入。
Returns the number of characters referred to by the string reference. Equivalent to size () and length ().
Returns the number of (potentially overlapping) occurrences of the string str in this string reference.
若 cs is Qt.CaseSensitive (default), the search is case sensitive; otherwise the search is case insensitive.
该函数在 Qt 4.8 引入。
另请参阅 QString.count (), contains ()，和 indexOf ().
此函数重载 count ().
Returns the number of occurrences of the character ch in the string reference.
若 cs is Qt.CaseSensitive (default), the search is case sensitive; otherwise the search is case insensitive.
该函数在 Qt 4.8 引入。
另请参阅 QString.count (), contains ()，和 indexOf ().
如同 unicode ().
Returns true if the string reference ends with str ; otherwise returns false.
若 cs is Qt.CaseSensitive (default), the search is case sensitive; otherwise the search is case insensitive.
该函数在 Qt 4.8 引入。
另请参阅 QString.endsWith () 和 startsWith ().
此函数重载 endsWith ().
Returns true if the string reference ends with ch ; otherwise returns false.
若 cs is Qt.CaseSensitive (default), the search is case sensitive; otherwise the search is case insensitive.
该函数在 Qt 4.8 引入。
另请参阅 QString.endsWith () 和 endsWith ().
此函数重载 endsWith ().
该函数在 Qt 4.8 引入。
另请参阅 QString.endsWith () 和 endsWith ().
Returns the index position of the first occurrence of the string str in this string reference, searching forward from index position from . Returns -1 if str 找不到。
若 cs is Qt.CaseSensitive (default), the search is case sensitive; otherwise the search is case insensitive.
若 from is -1, the search starts at the last character; if it is -2, at the next to last character and so on.
该函数在 Qt 4.8 引入。
另请参阅 QString.indexOf (), lastIndexOf (), contains ()，和 count ().
Returns the index position of the first occurrence of the string str in this string reference, searching forward from index position from . Returns -1 if str 找不到。
若 cs is Qt.CaseSensitive (default), the search is case sensitive; otherwise the search is case insensitive.
若 from is -1, the search starts at the last character; if it is -2, at the next to last character and so on.
该函数在 Qt 4.8 引入。
另请参阅 QString.indexOf (), lastIndexOf (), contains ()，和 count ().
此函数重载 indexOf ().
Returns the index position of the first occurrence of the character ch in the string reference, searching forward from index position from . Returns -1 if ch could not be found.
该函数在 Qt 4.8 引入。
另请参阅 QString.indexOf (), lastIndexOf (), contains ()，和 count ().
Returns true if the string reference has no characters; otherwise returns false.
A string reference is empty if its size is zero.
另请参阅 size ().
返回 true 若 string () returns a null pointer or a pointer to a null string; otherwise returns true.
另请参阅 size ().
Returns the index position of the last occurrence of the string str in this string reference, searching backward from index position from 。若 from is -1 (default), the search starts at the last character; if from is -2, at the next to last character and so on. Returns -1 if str 不是 found.
若 cs is Qt.CaseSensitive (default), the search is case sensitive; otherwise the search is case insensitive.
该函数在 Qt 4.8 引入。
另请参阅 QString.lastIndexOf (), indexOf (), contains ()，和 count ().
此函数重载 lastIndexOf ().
Returns the index position of the last occurrence of the character ch , searching backward from position from .
该函数在 Qt 4.8 引入。
另请参阅 QString.lastIndexOf (), indexOf (), contains ()，和 count ().
此函数重载 lastIndexOf ().
Returns the index position of the last occurrence of the string str in this string reference, searching backward from index position from 。若 from is -1 (default), the search starts at the last character; if from is -2, at the next to last character and so on. Returns -1 if str 不是 found.
若 cs is Qt.CaseSensitive (default), the search is case sensitive; otherwise the search is case insensitive.
该函数在 Qt 4.8 引入。
另请参阅 QString.lastIndexOf (), indexOf (), contains ()，和 count ().
Returns the number of characters referred to by the string reference. Equivalent to size () and count ().
Compares s1 with s2 and returns an integer less than, equal to, or greater than zero if s1 is less than, equal to, or greater than s2 .
The comparison is performed in a locale- and also platform-dependent manner. Use this function to present sorted lists of strings to the user.
On Mac OS X, this function compares according the "Order for sorted lists" setting in the International prefereces panel.
该函数在 Qt 4.5 引入。
另请参阅 compare () and QTextCodec.locale ().
这是重载函数。
Compares s1 with s2 and returns an integer less than, equal to, or greater than zero if s1 is less than, equal to, or greater than s2 .
The comparison is performed in a locale- and also platform-dependent manner. Use this function to present sorted lists of strings to the user.
该函数在 Qt 4.5 引入。
这是重载函数。
Compares this string with the other string and returns an integer less than, equal to, or greater than zero if this string is less than, equal to, or greater than the other string.
The comparison is performed in a locale- and also platform-dependent manner. Use this function to present sorted lists of strings to the user.
该函数在 Qt 4.5 引入。
这是重载函数。
Compares this string with the other string and returns an integer less than, equal to, or greater than zero if this string is less than, equal to, or greater than the other string.
The comparison is performed in a locale- and also platform-dependent manner. Use this function to present sorted lists of strings to the user.
该函数在 Qt 4.5 引入。
Returns the starting position in the referenced string that is referred to by the string reference.
Returns the number of characters referred to by the string reference. Equivalent to length () 和 count ().
Returns true if the string reference starts with str ; otherwise returns false.
若 cs is Qt.CaseSensitive (default), the search is case sensitive; otherwise the search is case insensitive.
该函数在 Qt 4.8 引入。
另请参阅 QString.startsWith () 和 endsWith ().
此函数重载 startsWith ().
该函数在 Qt 4.8 引入。
另请参阅 QString.startsWith () 和 endsWith ().
此函数重载 startsWith ().
该函数在 Qt 4.8 引入。
另请参阅 QString.startsWith () 和 endsWith ().
Returns a pointer to the string referred to by the string reference, or 0 if it does not reference a string.
另请参阅 unicode ().
Returns an 8-bit representation of the string as a QByteArray .
If a codec has been set using QTextCodec.setCodecForCStrings (), it is used to convert Unicode to 8-bit char; otherwise this function does the same as toLatin1 ().
Note that, despite the name, this function does not necessarily return an US-ASCII (ANSI X3.4-1986) string and its result may not be US-ASCII compatible.
该函数在 Qt 4.8 引入。
另请参阅 toLatin1 (), toUtf8 (), toLocal8Bit ()，和 QTextCodec .
Returns a Latin-1 representation of the string as a QByteArray .
The returned byte array is undefined if the string contains non-Latin1 characters. Those characters may be suppressed or replaced with a question mark.
该函数在 Qt 4.8 引入。
另请参阅 toAscii (), toUtf8 (), toLocal8Bit ()，和 QTextCodec .
Returns the local 8-bit representation of the string as a QByteArray . The returned byte array is undefined if the string contains characters not supported by the local 8-bit encoding.
QTextCodec.codecForLocale () is used to perform the conversion from Unicode. If the locale encoding could not be determined, this function does the same as toLatin1 ().
If this string contains any characters that cannot be encoded in the locale, the returned byte array is undefined. Those characters may be suppressed or replaced by another.
该函数在 Qt 4.8 引入。
另请参阅 toAscii (), toLatin1 (), toUtf8 ()，和 QTextCodec .
Returns a copy of the string reference as a QString 对象。
If the string reference is not a complete reference of the string (meaning that position () is 0 and size () 等于 string ()-> size ()), this function will allocate a new string to return.
另请参阅 string ().
Returns a UCS-4/UTF-32 representation of the string as a QVector <uint>.
UCS-4 is a Unicode codec and is lossless. All characters from this string can be encoded in UCS-4.
该函数在 Qt 4.8 引入。
另请参阅 toAscii (), toLatin1 (), toLocal8Bit ()，和 QTextCodec .
Returns a UTF-8 representation of the string as a QByteArray .
UTF-8 is a Unicode codec and can represent all characters in a Unicode string like QString .
However, in the Unicode range, there are certain codepoints that are not considered characters. The Unicode standard reserves the last two codepoints in each Unicode Plane (U+FFFE, U+FFFF, U+1FFFE, U+1FFFF, U+2FFFE, etc.), as well as 16 codepoints in the range U+FDD0..U+FDDF, inclusive, as non-characters. If any of those appear in the string, they may be discarded and will not appear in the UTF-8 representation, or they may be replaced by one or more replacement characters.
该函数在 Qt 4.8 引入。
另请参阅 toAscii (), toLatin1 (), toLocal8Bit ()，和 QTextCodec .
Returns a Unicode representation of the string reference. Since the data stems directly from the referenced string, it is not null-terminated unless the string reference includes the string's null terminator.
另请参阅 string ().
