Another basic C++ question

In C, this is a way to define a struct so that you can refer to it thereafter in code without the struct keyword. In C++, the two methods are more or less identical. There''s very little reason to use this idiom in C++.

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"Sneftel is correct, if rather vulgar." --Flarelocke

Nothing really, not in c++ anyway. If I recall correctly, in the old days of C programming you had to typedef you structs if you wanted to declare more than one. For example

typdef struct //you don''t actually need _STR
{
    char* str;
    int   numchars
}STR;

// now you can declare them as:

STR foo;
STR bar;

// but in c++ the following is the equivalent of the above:

struct STR
{
    char* str;
    int   numchars
};


 

Thanks!

You said they are almost identical, so, what is the small difference?
Whit this method, can I use _STR instead of STR identifier to declare a structure?

The small difference is that the C way really screws things up if you want to do templated structs. You can indeed use either _STR or STR if you do it that way.

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"Sneftel is correct, if rather vulgar." --Flarelocke

There are also small differences in exported symbol names (only really important if you''re writing a linker), valid member function names (not important if you''re using the struct as POD) and namespace pollution.