string transform with different input and output

[edgekaos]

Is method 2 valid?

Method 1:
wstring input = L"STRING";
wstring output = input;
transform(output.begin(), output.end(), output.begin(), towupper);

Method 2:
wstring input = L"STRING";
wstring output;
transform(input.begin(), input.end(), output.begin(), towupper);

I"m seeing crash under Visual Studio 2003 with method2.

[int2str]

edgekaos wrote:

Is method 2 valid?

Method 2:
wstring input = L"STRING";
wstring output;
transform(input.begin(), input.end(), output.begin(), towupper);

No, it's not. The output iterator needs to be the same length as the
input iterator.

Cheers,
Andre

[int2str]

Sorry to reply to my own post, but...

in*****@gmail.com wrote:

edgekaos wrote:

Is method 2 valid?

Method 2:
wstring input = L"STRING";
wstring output;
transform(input.begin(), input.end(), output.begin(), towupper);

No, it's not. The output iterator needs to be the same length as the
input iterator.

OR, you can also use std::back_inserter(). Like so:

string input = "Hello World!";
string output;

transform( input.begin(), input.end(), back_inserter( output ), toupper
);

Cheers,
Andre

[Andrey Tarasevich]

edgekaos wrote:

Is method 2 valid?

Method 1:
wstring input = L"STRING";
wstring output = input;
transform(output.begin(), output.end(), output.begin(), towupper);

Method 2:
wstring input = L"STRING";
wstring output;
transform(input.begin(), input.end(), output.begin(), towupper);

I"m seeing crash under Visual Studio 2003 with method2.

The latter method is not valid. In order to make it valid you should either
pre-set the size of the destination string

wstring input = L"STRING";
wstring output(input.length(), 0);

transform(input.begin(), input.end(), output.begin(), towupper);

or use the 'back_insert_iterator' as the output iterator (see 'int2str's
messages), optionally reserving the required amount of memory in advance

wstring input = L"STRING";
wstring output;

output.reserve(input.length()); // <- optional

transform(input.begin(), input.end(), back_inserter(output), towupper);

--
Best regards,
Andrey Tarasevich