[RESOLVED] STL string concatenation does not work.

Hello,

Why it's not working and how to make it work?

Code:

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    string str = "hello" + " *** ";

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Thank you.

Quote:

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Originally Posted by vincegata

Why it's not working and how to make it work?

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It's because "hello" and " *** " aren't of the string type. They're const char* and they cannot be added like that.

But fortunately there's a string constructor that takes a const char* so this should work,

Code:

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    string str = string("hello") + string(" *** ");

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-- thank you.

It's possible to avoid the explicit conversions I suggested. For example you can do this,

Code:

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string str = "hello";
str = str + " *** ";

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Here instead implicit conversions (from const char* to string) take place behind the scene.

Quote:

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Originally Posted by nuzzle

It's possible to avoid the explicit conversions I suggested. For example you can do this,

Code:

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string str = "hello";
str = str + " *** ";

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Here instead implicit conversions (from const char* to string) take place behind the scene.

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That's the way I did it but I need to build long strings from pieces so I had to declare several variables.

If you know in advance that the string will become very long, it could make sense to call "reserve" upfront. This way there will be less memory reallocations during the string building process. But this is only important when it has to be quick.

> If you know in advance that the string will become very long, it could make sense to call "reserve" upfront. This way there will be less memory reallocations during the string building process. But this is only important when it has to be quick.

Actually, it does have to be fast, I'll keep "reserve" in mind, I am just not at the stage to optimize the strings -- thx.