In QT3, I can use the following code in the .h file of my class:
typedef QMap < QString, QString > SubNameVariableMap;
typedef QMap < QString, SubNameVariableMap > NameVariableMap;
typedef SubNameVariableMap::value_type SubNameVariableMapValue ;
typedef NameVariableMap::value_type NameVariableMapValue;

but in QT4, a compilation error comes:
error:value_type in class QMap<QString, QString> does not name a type.

Can anyone tell me what's going on?
How can I solve this?