c++ custom string format using stringstreams

Question

I am trying to use the new stringstreams method to convert certain float+int combination into certain format but trying to see if there is any better way to handle this:

Now using //string String = static_cast( &(ostringstream() << Number) )->str(); kind of mode - How can I get this stored into a string form of the format - "1.10(3)". Precision is equal to decimals. The catch here is none of these values are constants. Even if the solution can't be an in-line function or stringstreams - it's fine as long as it's generic enough. Also note that in the end the plan is to use this string into GDI text string.

Thanks in advance - if any one can help.

Here is my current sample code(and looking for an alternate efficient way to get this done):

string Convert(float number,int decimals)
{
std::ostringstream buff;
buff<<setprecision(decimals)<<fixed<<number;
return buff.str();
}


float f=1.1;     // this can have any values from 1,1.5 or 1.52
int decimals=2;  //dynamic number - calculated by other means - not a fixed number
int i=3;         // some dynamic number as well - calculated by other means

string s=Convert(f,decimals)+"("+Convert(i,0)+")";  // output - 1.10(3)

Related / dupe: stackoverflow.com/questions/2839592/…

Ciro Santilli OurBigBook.com
– Ciro Santilli OurBigBook.com

2013-12-18 13:16:10 +00:00
Commented Dec 18, 2013 at 13:16 — Ciro Santilli OurBigBook.com
– Ciro Santilli OurBigBook.com, Commented Dec 18, 2013 at 13:16

zakinster · Accepted Answer · 2013-04-25 13:34:33Z

6

You can use std::fixed, std::setprecision, std::setw and std::setfill defined in <iomanip> :

float f=1.1;  
int decimals=2;
int i=3;
ostringstream ss;
ss << std::fixed << std::setprecision(decimals) << f << '(' << i << ')';
string str = ss.str();

Which outputs :

1.10(3)

You can also configure the stringstream and keep this configuration :

ostringstream ss;
ss.precision(5);
ss.setf(std::ios::fixed);

EDIT

You can still do this in one line if you really want to :

string str = ((ostringstream&)(ostringstream() << fixed << setprecision(decimals) << f << '(' << i << ')')).str();

If you want a LPCWSTR (const wchar_t *) instead of a LPCSTR (const char*) you should use wstringstream instead of stringstream.

ostringstream ss;
string str = ss.str();
LPCSTR* c_str = str.c_str();

wostringstream wss;
wstring wstr = wss.str();
LPCWSTR* wc_str = wstr.c_str();

If you want a LPCTSTR (LPCSTR or LPCWSTR if UNICODE is defined), you can use some typedef like this :

typedef std::basic_string<TCHAR> tstring;
typedef std::basic_ostringstream<TCHAR , std::char_traits<TCHAR> > tstringstream;

tostringstream tss;
tstring tstr = tss.str();
LPCTSTR* tc_str = tstr.c_str();

TCHAR is a char * if UNICODE is not defined in your project and a wchar_t * if UNICODE is defined.

edited Apr 25, 2013 at 13:34

answered Apr 25, 2013 at 12:32

zakinster

10.7k1 gold badge45 silver badges54 bronze badges

Sign up to request clarification or add additional context in comments.

12 Comments

ejuser Over a year ago

zakinster - thanks - but here you are hard-coding "2" for setw(2). Wanted to avoid that hard-coded value there.

zakinster Over a year ago

@ejuset ok you didn't specify in your first post that you were looking for an alternative to this approach.

ejuser Over a year ago

Thanks @zakinster - Perfect.. Though could have been better with some kind of "complex" static_cast to make it into a one-liner.. but this is definitely better than what I have as a convert function.. Thanks.

zakinster Over a year ago

@ejuser you can still do this in one line but it's not pretty (see my last edit).

ejuser Over a year ago

Awesome.. Thank you !! I like the one liner - you have ( leaving aside the the content of the line - code would be much more readable due to less number of lines:)

|

Collectives™ on Stack Overflow

c++ custom string format using stringstreams

1 Answer 1

12 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

12 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related