RTTI - how to ?

[Bit Byte]

I am passing data as a string arg to a function. I'd like to determine
whether the data is 'text' (i.e. alpha || alphanumeric), ineteger or
double).

enum
{
TEXT,
INTEGER,
DOUBLE
}DataType ;

DataType foo(const string& arg)
{
//determine data type
...
};

Any ideas how to do this ?

[Victor Bazarov]

Bit Byte wrote:

I am passing data as a string arg to a function. I'd like to determine
whether the data is 'text' (i.e. alpha || alphanumeric), ineteger or
double).

enum
{
TEXT,
INTEGER,
DOUBLE
}DataType ;

DataType foo(const string& arg)
{
//determine data type
...
};

Any ideas how to do this ?

Look up functions 'isalpha', 'isdigit', etc. The usual algorithm is: if
you can convert it *entirely* into a number, it's a number. If you try
converting and you have some symbols left over, it's not a number.

Also, read FAQ 5.2.

V
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[Andrey Tarasevich]

Bit Byte wrote:

I am passing data as a string arg to a function. I'd like to determine
whether the data is 'text' (i.e. alpha || alphanumeric), ineteger or
double).

enum
{
TEXT,
INTEGER,
DOUBLE
}DataType ;

DataType foo(const string& arg)
{
//determine data type
...
};

Any ideas how to do this ?

First you'd have to come up with a list of criteria that define your 'text',
'integer' and 'double'. It is probably natural thing to do to arrange the
criteria in hierarchical fashion: first test for 'double', then for 'integer'
and the rest is 'text'. But what about the details of each format? Are you
planning to use the C++ language definitions for integer and floating-point
literals? Or maybe formats recognized by string conversion functions (like
'scanf' and 'strtol')? Or you have something else in mind? For example, is '0x1'
an 'integer' or a 'text'? Is '1e+5' an allowed format of your 'double'? What
about ' 5 ' (with these extra spaces)? Is it an 'integer' or a 'text'?

--
Best regards,
Andrey Tarasevich