stringstream leading characters with fill and width

stringstream leading characters with fill and width

David Sopala

Member #5,056

September 2004

Ok what I need to get is a file name that is in the format of:
001
002
003
...
010
I need those leading 0's

Neil said it was possible to use stringstream.

my code is:

xx is a for loop variable it just increments starting at 1.
I can't seem to figure out why I can't get the leading 0's to show up. Maybe someone who has used this before could shed some light on the situation?

stringstream ss;
char prev = cout.fill('0');
cout.width(3);
ss << xx;
temp = ss.str();

got it sorta working with this code

ss.width(3);
ss.fill('0');
ss << xx;
temp = ss.str();
ss.ignore(3);

although the ignore ignores the next 3 characters and not the current buffer. I did try flushing as well, but it seemed to have no effect.

This seems to be the solution as put forth by the standard:

ss.str("");

Peter Wang

Member #23

April 2000

Do I need to /duck if I suggest sprintf, snprintf?

edit: still, it doesn't hurt to learn something new.

#include <iostream>
#include <iomanip>
#include <sstream>

using namespace std;

int main()
{
    stringstream ss;
    ss << setfill('0') << setw(4) << 42;
    cout << ss.str() << endl;
}

David Sopala

Member #5,056

September 2004

This works with strings, which I am using so it saves a step. sprintf would be great if your looking for c and not C++ or using char*'s and not string classes.

The only problem was that how to clear the buffer was not clearly defined from where I found it.

The proper method being:

ss.str("");

verthex

Member #11,340

September 2009

I'm not sure if this will help you but the way I converted my strings to wide chars was like this. I take ints and convert them to string, then I concatenate a large number of them to a single string and then copy them over to a wchar*. Hope it helps.

#SelectExpand
  1std::string sX, sY, sZ;
std::string comma = ",";
std::string Rp = ")";
std::string Lp = "(";
std::string coordinates;
int ix, iy, iz;
ix = 0;
iy = 0;
iz = 0;
 10
std::stringstream convert; // stringstream used for the conversion
convert <<ix;//add the value of Number to the characters in the stream
sX = convert.str();//set Result to the content of the stream
convert.str("");
 15
convert <<iy;//add the value of Number to the characters in the stream
sY = convert.str();//set Result to the content of the stream
convert.str("");
 19
convert <<iz;//add the value of Number to the characters in the stream
sZ = convert.str();//set Result to the content of the stream
convert.str("");
 23
coordinates = Lp + sX + comma + sY + comma + sZ + Rp;
 25
wchar_t *p=new wchar_t[coordinates.size()];
 27
for(std::string::size_type i=0; i<coordinates.size(); ++i)
  p[i]=coordinates[i];

EDIT

What you could do is take your integer and convert that to a string and then use the size() method to find the number of single integers in your first integer. I did the below code in the a.cc text input without compiling it so it might not work.

#SelectExpand
  1int Inumber = 100;//convert this string
  2string Snumber;
  3std::stringstream convert;
  4
  5convert<<Inumber;
  6Snumber = convert.str();
  7//find the size
  8int size = Snumber.size();
  9//now take the size and subtract it from the number of max leading zeros
 10int leading_zeros = 3 - size;
 11//now concatenate the leading_zero count to the Snumber string.
 12string leading_string;
 13
 14for (int count = 0 ; count < leading_zeros; count++)
 15    leading_string += "0";
 16
 17leading_string = leading_string + Snumber;

LennyLen

Member #5,313

December 2004

verthex said:

I did the below code in the a.cc text input without compiling it so it might not work.

It doesn't really matter whether that way would work or not as it's completely the wrong way to do it. The way Peter demonstrated is the best way to do it in C++.

verthex

Member #11,340

September 2009

LennyLen said:

It doesn't really matter whether that way would work or not as it's completely the wrong way to do it. The way Peter demonstrated is the best way to do it in C++.

Oh, I didn't know he solved it. I wasn't sure what Adam meant after he posted the answer.

Peter Wang

Member #23

April 2000

verthex said:

Adam

Where do you get this stuff?

David Sopala

Member #5,056

September 2004

Who is Adam? Now I am confused.

verthex