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# mysqlpp::ColData_Tmpl< Str > Class Template Reference

Template for string data that can convert itself to any standard C data type. More...

`#include <coldata.h>`

Collaboration diagram for mysqlpp::ColData_Tmpl< Str >:

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List of all members.

## Public Methods

| ColData_Tmpl ()
| Default constructor.
| ColData_Tmpl (bool n, mysql_type_info t=mysql_type_info::string_type)
| Constructor allowing you to set the null flag and the type data.
| ColData_Tmpl (const char *str, mysql_type_info t=mysql_type_info::string_type, bool n=false)
| Full constructor.
mysql_type_info | type () const
| Get this object's current MySQL type.
bool | quote_q () const
| Returns true if data of this type should be quoted, false otherwise.
bool | escape_q () const
| Returns true if data of this type should be escaped, false otherwise.
template<class Type> Type | conv (Type dummy) const
| Template for converting data from one type to another.
void | it_is_null ()
| Set a flag indicating that this object is a SQL null.
const bool | is_null () const
| Returns true if this object is a SQL null.
const std::string & | get_string () const
| Returns the string form of this object's data.
| operator cchar * () const
| Returns a const char pointer to the string form of this object's 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.
template<class T, class B> | operator Null () const
| Converts this object to a SQL null.

## Detailed Description

### template<class Str>
class mysqlpp::ColData_Tmpl< Str >

Template for string data that can convert itself to any standard C data type.

Do not use this class directly. Use the typedef ColData or MutableColData instead. ColData is a `ColData_Tmpl<const` `std::string>` and MutableColData is a `ColData_Tmpl<std::string>`.

The ColData types add to the C++ string type the ability to automatically convert the string data to any of the basic C types. This is important with SQL, because all data coming from the database is in string form. MySQL++ uses this class internally to hold the data it receives from the server, so you can use it naturally, because it does the conversions implicitly:

    ColData("12.86") + 2.0

That works fine, but be careful. If you had said this instead:

    ColData("12.86") + 2

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

If these automatic conversions scare you, define the micro NO_BINARY_OPERS to disable this behavior.

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

template<class Str>
mysqlpp::ColData_Tmpl< Str >::ColData_Tmpl | ( |  | ) | `[inline]`

| Default constructor. Null flag is set to false, type data is not set, and string data is left empty. It's probably a bad idea to use this ctor, becuase there's no way to set the type data once the object's constructed.

template<class Str>
mysqlpp::ColData_Tmpl< Str >::ColData_Tmpl | ( | bool | n,
|  | mysql_type_info | t = mysql_type_info::string_type
| ) | `[inline, explicit]`

Constructor allowing you to set the null flag and the type data.

Parameters:

  n | if true, data is a SQL null
  t | MySQL type information for data being stored

template<class Str>
mysqlpp::ColData_Tmpl< Str >::ColData_Tmpl | ( | const char * | str,
|  | mysql_type_info | t = mysql_type_info::string_type,
|  | bool | n = false
| ) | `[inline, explicit]`

Full constructor.

Parameters:

  str | the string this object represents
  t | MySQL type information for data within str
  n | if true, str is a SQL null

## Member Function Documentation

template<class Str>
template<class T, class B>
mysqlpp::ColData_Tmpl< Str >::operator Null< T, B > | ( |  | ) | const

| Converts this object to a SQL null. Returns null directly if the string data held by the object is exactly equal to "NULL". Else, it data.

The documentation for this class was generated from the following file:

- coldata.h