mysqlpp::String Class Reference

A std::string work-alike that can convert itself from SQL text data formats to C++ data types. More...

#include <mystring.h>

Collaboration diagram for mysqlpp::String:

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List of all members.

Public Types

typedef const char value_type
 Type of the data stored in this object, when it is not equal to SQL null.
typedef size_t size_type
 Type of "size" integers.
typedef const char * const_iterator
 Type of iterators.
typedef const_iterator iterator
 Same as const_iterator because the data cannot be changed.

Public Member Functions

 String ()
 Default constructor.
 String (const String &other)
 Copy ctor.
 String (const char *str, size_type len, mysql_type_info type=mysql_type_info::string_type, bool is_null=false)
 Full constructor.
 String (const std::string &str, mysql_type_info type=mysql_type_info::string_type, bool is_null=false)
 C++ string version of full ctor.
 String (const char *str, mysql_type_info type=mysql_type_info::string_type, bool is_null=false)
 Null-terminated C string version of full ctor.
 ~String ()
 Destroy string.
void assign (const char *str, size_type len, mysql_type_info type=mysql_type_info::string_type, bool is_null=false)
 Assign raw data to this object.
void assign (const std::string &str, mysql_type_info type=mysql_type_info::string_type, bool is_null=false)
 Assign a C++ string to this object.
void assign (const char *str, mysql_type_info type=mysql_type_info::string_type, bool is_null=false)
 Assign a C string to this object.
char at (size_type pos) const
 Return a character within the string.
const_iterator begin () const
 Return iterator pointing to the first character of the string.
const char * c_str () const
 Return a const pointer to the string data.
template<class Type>
Type conv (Type) const
 Template for converting the column data to most any numeric data type.
template<class T, class B>
Null< T, B > conv (Null< T, B >) const
 Overload of conv() for types wrapped with Null<>.
int compare (const String &other) const
 Lexically compare this string to another.
int compare (const std::string &other) const
 Lexically compare this string to another.
int compare (size_type pos, size_type num, std::string &other) const
 Lexically compare this string to another.
int compare (const char *other) const
 Lexically compare this string to another.
int compare (size_type pos, size_type num, const char *other) const
 Lexically compare this string to another.
const char * data () const
 Raw access to the underlying buffer, with no C string interpretation.
bool empty () const
 Returns true if size() == 0.
const_iterator end () const
 Return iterator pointing to one past the last character of the string.
bool escape_q () const
 Returns true if data of this type should be escaped, false otherwise.
bool is_null () const
 Returns true if this object is a SQL null.
void it_is_null ()
 Set a flag indicating that this object is a SQL null.
size_type length () const
 Return number of bytes in the string.
size_type max_size () const
 Return the maximum number of characters in the string.
bool quote_q () const
 Returns true if data of this type should be quoted, false otherwise.
size_type size () const
 Return number of bytes in string.
void strip_leading_blanks (std::string &s) const
 Returns a copy of our internal string without leading blanks.
void to_string (std::string &s) const
 Copies this object's data into a C++ string.
mysql_type_info type () const
 Get this object's current MySQL type.
Stringoperator= (const std::string &rhs)
 Assignment operator, from C++ string.
Stringoperator= (const char *str)
 Assignment operator, from C string.
Stringoperator= (const String &other)
 Assignment operator, from other String.
template<typename T>
bool operator== (const T &rhs) const
 Equality comparison operator.
bool operator== (const mysqlpp::null_type &) const
 Equality comparison operator.
template<typename T>
bool operator!= (const T &rhs) const
 Inequality comparison operator.
bool operator!= (const mysqlpp::null_type &) const
 Inequality comparison operator.
char operator[] (size_type pos) const
 Return a character within the string.
 operator const char * () const
 Returns a const char pointer to the object's raw data.
 operator signed char () const
 Converts this object's string data to a signed char.
 operator unsigned char () const
 Converts this object's string data to an unsigned char.
 operator int () const
 Converts this object's string data to an int.
 operator unsigned int () const
 Converts this object's string data to an unsigned int.
 operator short int () const
 Converts this object's string data to a short int.
 operator unsigned short int () const
 Converts this object's string data to an unsigned short int.
 operator long int () const
 Converts this object's string data to a long int.
 operator unsigned long int () const
 Converts this object's string data to an unsigned long int.
 operator longlong () const
 Converts this object's string data to the platform- specific 'longlong' type, usually a 64-bit integer.
 operator ulonglong () const
 Converts this object's string data to the platform- specific 'ulonglong' type, usually a 64-bit unsigned integer.
 operator float () const
 Converts this object's string data to a float.
 operator double () const
 Converts this object's string data to a double.
 operator bool () const
 Converts this object's string data to a bool.
 operator Date () const
 Converts this object's string data to a mysqlpp::Date.
 operator DateTime () const
 Converts this object's string data to a mysqlpp::DateTime.
 operator Time () const
 Converts this object's string data to a mysqlpp::Time.
template<class T, class B>
 operator Null () const
 Converts the String to a nullable data type.

Friends

class SQLTypeAdapter

Detailed Description

A std::string work-alike that can convert itself from SQL text data formats to C++ data types.

This class is an intermediate form for a SQL field, normally converted to a more useful native C++ type, not used directly. The only exception is in dealing with BLOB data, which stays in String form for efficiency and to avoid corrupting the data with facile conversions. Even then, it's best to use it through the typedef aliases like sql_blob in sql_types.h, in case we later change this underlying representation.

String's implicit conversion operators let you can use these objects naturally:

 String("12.86") + 2.0 

That will give you 14.86 (approximately) as you expect, but be careful not to get tripped up by C++'s type conversion rules. If you had said this instead:

 String("12.86") + 2 

the result would be 14 because 2 is an integer, and C++'s type conversion rules put the String object in an integer context.

You can disable the operator overloads that allow these things by defining MYSQLPP_NO_BINARY_OPERS.

This class also has some basic information about the type of data stored in it, to allow it to do the conversions more intelligently than a trivial implementation would allow.


Constructor & Destructor Documentation

mysqlpp::String::String (  )  [inline]

Default constructor.

An object constructed this way is essentially useless, but sometimes you just need to construct a default object.

mysqlpp::String::String ( const String other  )  [inline]

Copy ctor.

Parameters:
other the other String object
This ctor only copies the pointer to the other String's data buffer and increments its reference counter. If you need a deep copy, use one of the ctors that takes a string.

mysqlpp::String::String ( const char *  str,
size_type  len,
mysql_type_info  type = mysql_type_info::string_type,
bool  is_null = false 
) [inline, explicit]

Full constructor.

Parameters:
str the string this object represents, or 0 for SQL null
len the length of the string; embedded nulls are legal
type MySQL type information for data within str
is_null string represents a SQL null, not literal data
The resulting object will contain a copy of the string buffer. The buffer will actually be 1 byte longer than the value given for len, to hold a null terminator for safety. We do this because this ctor may be used for things other than null-terminated C strings. (e.g. BLOB data)

mysqlpp::String::String ( const std::string &  str,
mysql_type_info  type = mysql_type_info::string_type,
bool  is_null = false 
) [inline, explicit]

C++ string version of full ctor.

Parameters:
str the string this object represents, or 0 for SQL null
type MySQL type information for data within str
is_null string represents a SQL null, not literal data
The resulting object will contain a copy of the string buffer.

mysqlpp::String::String ( const char *  str,
mysql_type_info  type = mysql_type_info::string_type,
bool  is_null = false 
) [inline, explicit]

Null-terminated C string version of full ctor.

Parameters:
str the string this object represents, or 0 for SQL null
type MySQL type information for data within str
is_null string represents a SQL null, not literal data
The resulting object will contain a copy of the string buffer.


Member Function Documentation

void mysqlpp::String::assign ( const char *  str,
mysql_type_info  type = mysql_type_info::string_type,
bool  is_null = false 
) [inline]

Assign a C string to this object.

This parallels the ctor with the same parameters, for when you must do a 2-step create, or when you want to reassign the data without creating a String temporary to get around the fact that operator=() can only take one parameter.

void mysqlpp::String::assign ( const std::string &  str,
mysql_type_info  type = mysql_type_info::string_type,
bool  is_null = false 
) [inline]

Assign a C++ string to this object.

This parallels the ctor with the same parameters, for when you must do a 2-step create, or when you want to reassign the data without creating a String temporary to get around the fact that operator=() can only take one parameter.

void mysqlpp::String::assign ( const char *  str,
size_type  len,
mysql_type_info  type = mysql_type_info::string_type,
bool  is_null = false 
) [inline]

Assign raw data to this object.

This parallels the ctor with the same parameters, for when you must do a 2-step create, or when you want to reassign the data without creating a String temporary to get around the fact that operator=() can only take one parameter.

char mysqlpp::String::at ( size_type  pos  )  const

Return a character within the string.

Exceptions:
mysqlpp::BadIndex if the row is not initialized or there are less than i fields in the row.

int mysqlpp::String::compare ( size_type  pos,
size_type  num,
const char *  other 
) const

Lexically compare this string to another.

Parameters:
pos position within this string to begin comparison
num maximum number of characters within this string to use in comparison
other string to compare against this one
Return values:
< 0 if this string is lexically "less than" other
0 if this string is equal to other
> 0 if this string is lexically "greater than" other

int mysqlpp::String::compare ( const char *  other  )  const

Lexically compare this string to another.

Parameters:
other string to compare against this one
See also:
compare(size_type, size_type, const char*)

int mysqlpp::String::compare ( size_type  pos,
size_type  num,
std::string &  other 
) const

Lexically compare this string to another.

Parameters:
pos position within this string to begin comparison
num maximum number of characters within this string to use in comparison
other string to compare against this one
See also:
compare(size_type, size_type, const char*)

int mysqlpp::String::compare ( const std::string &  other  )  const

Lexically compare this string to another.

Parameters:
other string to compare against this one
See also:
compare(size_type, size_type, const char*)

int mysqlpp::String::compare ( const String other  )  const

Lexically compare this string to another.

Parameters:
other string to compare against this one
See also:
compare(size_type, size_type, const char*)

template<class T, class B>
Null<T, B> mysqlpp::String::conv ( Null< T, B >   )  const [inline]

Overload of conv() for types wrapped with Null<>.

If the String object was initialized with some string we recognize as a SQL null, we just return a copy of the global 'null' object converted to the requested type. Otherwise, we return the String's value wrapped in the Null<> template.

String::size_type mysqlpp::String::length (  )  const

Return number of bytes in the string.

Note that this doesn't count the number of characters in the string. If your database is configured to use an 8-bit character set, this is a distinction without a difference. But, if you're using UTF-8 in the database, you will need to "widen" the UTF-8 data to use a fixed-size character set like UCS-2 and count the characters that way. You might use std::wstring, for example.

size_type mysqlpp::String::max_size (  )  const [inline]

Return the maximum number of characters in the string.

Because this is a const string, this is just an alias for size(); its size is always equal to the amount of data currently stored.

template<class T, class B>
mysqlpp::String::operator Null (  )  const [inline]

Converts the String to a nullable data type.

This is just an implicit version of conv(Null<T, B>)

bool mysqlpp::String::operator!= ( const mysqlpp::null_type  )  const [inline]

Inequality comparison operator.

For checking object against MySQL++'s global null constant

template<typename T>
bool mysqlpp::String::operator!= ( const T &  rhs  )  const [inline]

Inequality comparison operator.

For comparing this object to any of the data types we have a compare() overload for.

String& mysqlpp::String::operator= ( const String other  )  [inline]

Assignment operator, from other String.

This only copies the pointer to the other String's data buffer and increments its reference counter. If you need a deep copy, assign a string to this object instead.

String& mysqlpp::String::operator= ( const char *  str  )  [inline]

Assignment operator, from C string.

This creates a copy of the entire string, not just a copy of the pointer.

bool mysqlpp::String::operator== ( const mysqlpp::null_type  )  const [inline]

Equality comparison operator.

For checking object against MySQL++'s global null constant

template<typename T>
bool mysqlpp::String::operator== ( const T &  rhs  )  const [inline]

Equality comparison operator.

For comparing this object to any of the data types we have a compare() overload for.

char mysqlpp::String::operator[] ( size_type  pos  )  const [inline]

Return a character within the string.

This function is just syntactic sugar, wrapping the at() method.

Exceptions:
mysqlpp::BadIndex if the string is not initialized or there are less than i fields in the string.

size_type mysqlpp::String::size (  )  const [inline]

Return number of bytes in string.

See commentary for length() about the difference between bytes and characters.

void mysqlpp::String::to_string ( std::string &  s  )  const

Copies this object's data into a C++ string.

If you know the data doesn't contain null characters (i.e. it's a typical string, not BLOB data), it's more efficient to just assign this object to anything taking const char*. (Or equivalently, call the data() method.) This copies a pointer to a buffer instead of copying the buffer's contents.


The documentation for this class was generated from the following files:
Generated on 20 Jun 2013 for MySQL++ by  doxygen 1.4.7