C++ string and arrays

Question

If string is just an array of chars, then is it considered bad coding to directly access an index of a string? for example...

 string test = "Hello"; 
 cout << text.[0];

 int lenOfTest = (int)test.length();
 for(int i = 0; i < lenOfTest; i++ ){
   cout << test[i];
 }

This is fine, except for text.[0], I guess that is some sort of typo — M.M
– M.M, Commented Apr 5, 2014 at 0:40
A std::string is not just an array of characters. It's a standard class, which overloads [] to access the elements of the string. — Barmar
– Barmar, Commented Apr 5, 2014 at 0:41

Massa · Accepted Answer · 2014-04-05 00:40:48Z

3

A std::string is not a simple array of char, although it is a container of char, and yes, you can access each of its elements normally. Just don't use the point before the open [ like you did in your second line.

answered Apr 5, 2014 at 0:40

Massa

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4 Comments

M.M Over a year ago

The std::string does wrap an array of char though, which you have full access to.

Enrico Granata Over a year ago

@MattMcNabb, one would actually hope you don't have full access to the underlying buffer. If you look at libc++, for instance, there are two buffers, only one of which is actually in use for a given instance - I would hope users don't get to muck with either fully and directly

M.M Over a year ago

You can get it via &s[0]. To be clear I should say "full access to the contents of", I guess; you can't reallocate it .

Massa Over a year ago

you also shouldn't write to the memory pointed to by &s[0] (nor c_str() or data()...) because it's UB.

lucasmoura · Accepted Answer · 2014-04-05 00:45:36Z

2

I don't think it is a bad practice to access a char element using the operator[], however keep in mind that accessing a character like this will not raise an exception in case a invalide position is being used. To raise an exception, use the string::at.

answered Apr 5, 2014 at 0:45

lucasmoura

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