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Programming-Idioms

  • Python
  • C++

Idiom #65 Format decimal number

From the real value x in [0,1], create its percentage string representation s with one digit after decimal point. E.g. 0.15625 -> "15.6%"

s = format(x, '.1%')
s = '%.1f%%' % (x * 100)
s = f"{x:.01%}"
s = '{:.1%}'.format(x)

.1 means only one digit after decimal point.
% handles the "multiplication" and shows the percentage sign.
#include <format>
auto s = std::format("{.1f}%", x * 100);

Based on C++20 <format>.
#include <stdio.h>
char s[7];
sprintf(s, "%.2lf%%", x * 100);
New implementation...
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programming-idioms.org 
s = format(x, '.1%')
s = '%.1f%%' % (x * 100)
s = f"{x:.01%}"
s = '{:.1%}'.format(x)
auto s = std::format("{.1f}%", x * 100);
char s[7];
sprintf(s, "%.2lf%%", x * 100);
string s = $"{x:p1}";
string percent = format("%.1f%%", x * 100.0);
var s = "${(x * 100).toStringAsFixed(1)}%";

s = "#{Float.round(x * 100, 1)}%"
write (*,'(F5.1,"%")') x*100.
s := fmt.Sprintf("%.1f%%", 100.0*x)
s = Numeric.showFFloat (Just 1) (100*x) "%"
const percentFormatter = new Intl.NumberFormat('en-US', {
  style: 'percent',
  maximumSignificantDigits: 3
});

const s = percentFormatter.format(x);
const s = Math.round (x * 1000) / 10 + '%'
String s = "%.1f%%".formatted(x * 100);
NumberFormat f = getPercentInstance();
f.setMaximumFractionDigits(1);
f.setRoundingMode(HALF_UP);
String s = f.format(x);
String s = new DecimalFormat("0.0%").format(x);
String s = format("{0,number,0.0%}", x);
s = string.format("%.1f%%", x*100)
local s = (x-x%10^-3)*100 .."%"
$s = number_format($x * 100.0, 1) . '%';
s :=format('%.1f%%', [100.0*x]);  
my $s = sprintf '%.1f%%', $x * 100;
s = "%.1f%%" % (100 * x)
let s = format!("{:.1}%", 100.0 * x);