Hi all,
Why doesn't the following unmanaged C++ code work as expected:
string s;
ostringstream strm(s); // This stream should store results in s
strm << 25;
cout << s << endl; // s still contains an empty string
cout << strm.str(); // but the stream internally contains "25" 3 1400
Bob Altman wrote: Hi all,
Why doesn't the following unmanaged C++ code work as expected:
string s; ostringstream strm(s); // This stream should store results in s
Where did you get the idea that the comment above is correct? The above
is just shorthand for:
ostringstream strm;
strm << s;
strm << 25; cout << s << endl; // s still contains an empty string
Right, since you've misunderstood what the ostringstream constructor does.
cout << strm.str(); // but the stream internally contains "25"
An ostringstream doesn't hold a reference to a string, but rather is
interoperable with strings. You need:
ostringstream strm;
strm << 25;
string s(strm.str());
//etc.
Tom
> > string s; ostringstream strm(s); // This stream should store results in s
Where did you get the idea that the comment above is correct?
"Beginning C++" by Ivor Horton, 1998 ed., page 802, states (apparently
incorrectly):
You can use an ostringstream object to format data into a string. For
instance, you could create a string object and an output string stream with
the statements:
string outBuffer;
ostringstream outStr(outBuffe r);
You can now use the insertion operators to write to outBuffer via outStr:
double number = 2.5;
outStr << "number = " << (number / 2);
As a result of the write to the string stream, outBuffer will contain
"Number = 1.25"... The string parameter to the string stream constructor is
a reference, so write operations for ostringstream objects act directly on
the string object.
Bob Altman wrote: string s; ostringstream strm(s); // This stream should store results in s
Where did you get the idea that the comment above is correct?
"Beginning C++" by Ivor Horton, 1998 ed., page 802, states (apparently incorrectly):
Dump that book and pick up a copy of "Accelerate d C++" by Andrew Koenig and
Barbara Moo. It's 1/3 the length, has far more content, and is actually
correct.
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