String question
Author
Part of my game engine relies on modifying strings based on the users input.
I was wondering if there is any way to extract a character from a string with a number as a parameter which tells how many places over to take it from. For example, say we have the string:
"bookmarks"
Say I needed to get the character that is 6 places over from the right (a), how would I go about doing that? I'm not sure if there is a function that does just that, but I honestly can't figure it out.
If you're using character arrays, you use [] just as in a normal array. If you're using std::string, it defines the [] operator and you use it exactly the same way as character arrays. [ EDIT: The only difference is that you can't assign values with the [] operator on strings. Apparently, you can. Never knew that :) ]
EDIT: or you can use the std::string::at() function. The at() function is actually safer than the [] operator, because it won't let you reference items outside the bounds of the string. If you try to, it will throw an exception.
[Edited by - v0dKA on July 22, 2006 5:40:50 PM]
EDIT: or you can use the std::string::at() function. The at() function is actually safer than the [] operator, because it won't let you reference items outside the bounds of the string. If you try to, it will throw an exception.
[Edited by - v0dKA on July 22, 2006 5:40:50 PM]
Author
Awesome, thanks. Sorry about the stupid question, I thought that only applied to char arrays.
Quote:
The only difference is that you can't assign values with the [] operator on strings.
Say what? - I probably misunderstood you, but the following will work:
std::string pData("abc");
pData[0] = 'z'; //zbc
Quote:Original post by raz0rQuote:
The only difference is that you can't assign values with the [] operator on strings.
Say what? - I probably misunderstood you, but the following will work:
std::string pData("abc");
pData[0] = 'z'; //zbc
Indeed. This is well-defined and standard. You wouldn't, of course, be able to do it to a const std::string, but then you couldn't to a const char* either.
I apologize in advance if this is a really stupid question, but, if std::strings are so awesome, what the heck are char arrays for anyways?
Quote:Original post by Anonymous Poster
I apologize in advance if this is a really stupid question, but, if std::strings are so awesome, what the heck are char arrays for anyways?
C-compatability.
Also, you can't use STL types across DLLs easily, so char arrays have to do.
Quote:Original post by Anonymous Poster
I apologize in advance if this is a really stupid question, but, if std::strings are so awesome, what the heck are char arrays for anyways?
This may or may not be a good idea, but char arrays are also used as byte arrays. A char data type is almost always exactly 1 byte long. So when you need an array of bytes, you simply use an array of chars.
It's bad to make assumptions, however. [ EDIT: There's nothing that guarantees that a char must be exactly one byte long. Oh yea there is, like, the C++ Standard itself :) ] I'm frankly not sure what you would use instead...
If you need an array of bytes, then create a byte array. No need to mess around with an array of chars instead. That's just confusing and you're bound to misuse it somewhere.
EDIT: My mistake. It seems that C++ doesn't have a "byte" type. I've been messing around with Java for too long...
EDIT: My mistake. It seems that C++ doesn't have a "byte" type. I've been messing around with Java for too long...
Quote:Original post by v0dKA
It's bad to make assumptions, however. There's nothing that guarantees that a char must be exactly one byte long. I'm frankly not sure what you would use instead...
I'm pretty sure that char is the only integral type of guarenteed size.
I believe the standard dicates that sizeof(char) == 1
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