how to make my own "setw" function ?

[gr8ash]

hey all,,,

i've been trying to make my own setw function that will do the same jop of setw,, this is my first year in college i study CIS in Jordan,,,

so, i made this code but6 i still have problims with float numbers, it seems like this code work on int numbers,, as u can see i've used my function in an example,,,,

plz help :D

#include<iostream.h>
#include<math.h>

    void myset( int w, float num ){
    int n=0;
    float num1 = fabs(num);
    while (num1 >= 1){
        num1/=10;
        n++;
    }

    for ( int i =0; i < w-n; i++){

    cout<< "0";
    }
    cout<<num<<endl;
}// end of the function 


main ()
{
    int w;
    float num;
    cout <<"enter the number"<<endl;
    cin >>num;
    cout<<"enter the number of the spaces"<<endl;
    cin >> w;

    myset(w, num);


}

[mvmalderen]

->First: Please post using code tags!
->Second: You have to know how to write manipulators :)

[vmanes]

What it looks like you're doing is displaying floats so that they will line up at the decimal point. Your loop to count digits is only counting the whole number portion.

If you're trying to mimic the setw( )manipulator, you're going to have to know how many digits fall after the decimal as well. For this, you need to know the precision in use, then subtract the number of digits in the whole number portion. Then there's the rounding of float values when displayed, depending on precision. Starting to sound pretty complex.

[ArkM]

May be it helps:
http://www.informit.com/articles/article.aspx?p=171014

[gr8ash]

thx everyone for ur help, and i'm really srry that i didnt include any comments on the program, i have just made it and i post it fast as i can,,,,

the main problim is that code can just count clumns for int number before the point ".",,, so i want to ask if there is anything in c++ can separate the numbers after the point, so that i can do the same process on the numbers after the point as integers numbers ... thx

[NathanOliver]

you could recive the numbers as strings then parsing through them find the decimal point then you will know how many digits are before the decimal point and how many are after for each number then its just a matter of displaying them as you want. maybe that will work for you but it is alot of coding and checking.

[gr8ash]

this is my code with the comments,,,,

#include<iostream.h>
#include<math.h>

    void myset( int , float  );// declare the function 




main ()
{
int w;
float num;
cout <<"enter the number"<<endl;
cin >>num;
cout<<"enter the number of the spaces"<<endl;
cin >> w;

myset(w, num);


}


    void myset( int w, float num ){ // inlization the function 

    int n=0;

    float num1 = fabs(num); // using fabs if the number < 0 
    while (num1 >= 1){
        num1/=10;// for example if the number is 100 it will be 10 then 1,, everyloop 
        n++;// every loop the num will be divided, that's how the program will know if the number is from tens or handrerds or thouthands .... etc
    }

    for ( int i =0; i < w-n; i++){

    cout<< " ";//print the spaces
    }
    cout<<num;

return;

}

[gr8ash]

NathanOliver,,, can u tell me exatly how to do that ???

[ArkM]

It seems that you can't write STL stream manipulator at this moment. Next time try to formulate the true problem, not your ideas about possible (incorrect) solutions of undefined problems.

Try this:

template<typename Number>
std::string lineUp(Number x, size_t prec, size_t dppos, size_t w = 0)
{
    std::ostringstream os;
    os << std::fixed << std::setprecision(prec) << x;
    size_t pos = os.str().find('.');
    if (pos == std::string::npos) {
        pos = os.str().size();
    }
    std::string s;
    if (pos < dppos)
        s.resize(dppos-pos,' ');
    s += os.str();
    if (w > 0 && s.size() < w)
        s.resize(w,' ');
    return s;
}
using std::cout;
int main()
{
    std::string s;
    s = lineUp(3.14159265358,6,8,16);
    cout << '>' << s << "<\n";
    cout << " 0123456789abcdef\n";
    s = lineUp(2009,6,8,16);
    cout << '>' << s << "<\n";
    cout << " 0123456789abcdef\n";
    s = lineUp(3.14f,6,8,16);
    cout << '>' << s << "<\n";
    cout << " 0123456789abcdef\n";
    return 0;
}