#include <iostream>
using namespace std;

int main()
{
    double B = 2006.008;
    printf(".2f", B);  

    return 0;
}

Output:

    2006.01

with blank spaces in the beginning

I want to replace those white spaces with underscores(_). Is there any syntax in print or any direct method to do that?

My desired output:

_______ 2006.01

CodePudding user response：

With std::format (C 20), you might do:

std::format("{:_>15.2}", B);

Demo

CodePudding user response：

or any direct method to do that?

One solution is to use the iomanip manipulators:

#include <iostream>
#include <iomanip>

int main()
{
    double B = 2006.008;
    printf(".2f\n", B);  // Original

    std::cout 
    << std::setfill('_') // The fill character
    << std::right        // right justify
    << std::setw(15)     // field width
    << std::fixed        // fixed precision
    << std::setprecision(2)  // 2 decimals
    << B;
}

Output:

        2006.01
________2006.01

CodePudding user response：

As in the comments suggested you can write a function for this, but not with printf().

#include <algorithm>
#include <iostream>

std::string formatNumber(double number)
{
    char buffer[15   1   2];
    sprintf(buffer, ".2f", number);  

    std::string s(buffer);
    std::replace(s.begin(), s.end(), ' ', '_');

    return s;
}

int main()
{
    double B = 2006.008;
    auto toPrint = formatNumber(B);

    std::cout << toPrint << std::endl;

    return 0;
}