blocks|key|1510689|text|您可以使用像Math::Round这样的模块|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1510690|use+Math::Round;
my+$rounded+=+round(+$float+);|code-block|syntax|javascript|1510691|或者你可以用一种粗糙的方式：|1510692|my+$rounded+=+sprintf+"%25.0f",+$float;|1510693|entityMap|0|LINK|mutability|MUTABLE|url|http://search.cpan.org/dist/Math-Round^0|6|B|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]]|C|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|Z|8|@]|9|@]|C|$]]|$1|K|3|L|5|F|7|10|8|@]|9|@]|C|$G|H]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]]]

You can either use a module like <A href="http://search.cpan.org/dist/Math-Round" rel="noreferrer">Math::Round</a>:

<pre><code>use Math::Round;
my $rounded = round( $float );
</code></pre>

Or you can do it the crude way:

<pre><code>my $rounded = sprintf "%.0f", $float;
</code></pre>

blocks|key|1725814|text|​|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1725815|如果您决定使用printf或sprintf，请注意它们使用的是Round+half+to+even方法。|offset|length|1725816|foreach+my+$i+(+0.5,+1.5,+2.5,+3.5+)+{
++++printf+"$i+->+%25.0f\n",+$i;
}
__END__
0.5+->+0
1.5+->+2
2.5+->+2
3.5+->+4|code-block|syntax|javascript|1725817|entityMap|0|LINK|mutability|MUTABLE|url|http://en.wikipedia.org/wiki/Rounding#Round_half_to_even^0|0|V|I|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@$D|U|E|V|1|W]]|A|$]]|$1|F|3|G|5|H|7|X|8|@]|9|@]|A|$I|J]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|L|$M|$5|N|O|P|A|$Q|R]]]]

If you decide to use printf or sprintf, note that they use the <a href="http://en.wikipedia.org/wiki/Rounding#Round_half_to_even" rel="noreferrer">Round half to even</a> method.

<pre><code>foreach my $i ( 0.5, 1.5, 2.5, 3.5 ) {
 printf "$i -&gt; %.0f\n", $i;
}
__END__
0.5 -&gt; 0
1.5 -&gt; 2
2.5 -&gt; 2
3.5 -&gt; 4
</code></pre>

blocks|key|1510957|text|下面将正数或负数四舍五入到给定的小数位：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1510958|sub+round+()
{
++++my+($x,+$pow10)+=+@_;
++++my+$a+=+10+**+$pow10;

++++return+(int($x+/+$a+%2B+(($x+<+0)+?+-0.5+:+0.5))+*+$a);
}|code-block|syntax|javascript|1510959|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

The following will round positive or negative numbers to a given decimal position:

<pre><code>sub round ()
{
 my ($x, $pow10) = @_;
 my $a = 10 ** $pow10;

 return (int($x / $a + (($x &lt; 0) ? -0.5 : 0.5)) * $a);
}
</code></pre>

blocks|key|1510764|text|以下是求和值的五种不同方法的示例。第一种是一种执行求和的天真方法(而且失败了)。第二个尝试使用sprintf()，但也失败了。第三个成功使用了sprintf()，而最后两个(第4个和第5个)使用了floor($value+%2B+0.5)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1510765|+use+strict;
+use+warnings;
+use+POSIX;

+my+@values+=+(26.67,62.51,62.51,62.51,68.82,79.39,79.39);
+my+$total1+=+0.00;
+my+$total2+=+0;
+my+$total3+=+0;
+my+$total4+=+0.00;
+my+$total5+=+0;
+my+$value1;
+my+$value2;
+my+$value3;
+my+$value4;
+my+$value5;

+foreach+$value1+(@values)
+{
++++++$value2+=+$value1;
++++++$value3+=+$value1;
++++++$value4+=+$value1;
++++++$value5+=+$value1;

++++++$total1+%2B=+$value1;

++++++$total2+%2B=+sprintf('%25d',+$value2+*+100);

++++++$value3+=+sprintf('%251.2f',+$value3);
++++++$value3+=~+s/\.//;
++++++$total3+%2B=+$value3;

++++++$total4+%2B=+$value4;

++++++$total5+%2B=+floor(($value5+*+100.0)+%2B+0.5);
+}

+$total1+*=+100;
+$total4+=+floor(($total4+*+100.0)+%2B+0.5);

+print+'$total1:+'.sprintf('%25011d',+$total1)."\n";
+print+'$total2:+'.sprintf('%25011d',+$total2)."\n";
+print+'$total3:+'.sprintf('%25011d',+$total3)."\n";
+print+'$total4:+'.sprintf('%25011d',+$total4)."\n";
+print+'$total5:+'.sprintf('%25011d',+$total5)."\n";

+exit(0);

+#$total1:+00000044179
+#$total2:+00000044179
+#$total3:+00000044180
+#$total4:+00000044180
+#$total5:+00000044180|code-block|syntax|javascript|1510766|请注意，可以用int($value+%2B+0.5)替换floor($value+%2B+0.5)，以消除对POSIX的依赖。|1510767|entityMap^0|1B|9|1Z|9|2Q|J|0|0|7|H|Q|J|1E|5|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]|$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@$9|X|A|Y|B|C]|$9|Z|A|10|B|C]|$9|11|A|12|B|C]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|13|8|@]|D|@]|E|$]]]|N|$]]

Following is a sample of five different ways to summate values. The first is a naive way to perform the summation (and fails). The second attempts to use <code>sprintf()</code>, but it too fails. The third uses <code>sprintf()</code> successfully while the final two (4th &amp; 5th) use <code>floor($value + 0.5)</code>.

<pre><code> use strict;
 use warnings;
 use POSIX;

 my @values = (26.67,62.51,62.51,62.51,68.82,79.39,79.39);
 my $total1 = 0.00;
 my $total2 = 0;
 my $total3 = 0;
 my $total4 = 0.00;
 my $total5 = 0;
 my $value1;
 my $value2;
 my $value3;
 my $value4;
 my $value5;

 foreach $value1 (@values)
 {
 $value2 = $value1;
 $value3 = $value1;
 $value4 = $value1;
 $value5 = $value1;

 $total1 += $value1;

 $total2 += sprintf('%d', $value2 * 100);

 $value3 = sprintf('%1.2f', $value3);
 $value3 =~ s/\.//;
 $total3 += $value3;

 $total4 += $value4;

 $total5 += floor(($value5 * 100.0) + 0.5);
 }

 $total1 *= 100;
 $total4 = floor(($total4 * 100.0) + 0.5);

 print '$total1: '.sprintf('%011d', $total1)."\n";
 print '$total2: '.sprintf('%011d', $total2)."\n";
 print '$total3: '.sprintf('%011d', $total3)."\n";
 print '$total4: '.sprintf('%011d', $total4)."\n";
 print '$total5: '.sprintf('%011d', $total5)."\n";

 exit(0);

 #$total1: 00000044179
 #$total2: 00000044179
 #$total3: 00000044180
 #$total4: 00000044180
 #$total5: 00000044180
</code></pre>

Note that <code>floor($value + 0.5)</code> can be replaced with <code>int($value + 0.5)</code> to remove the dependency on <code>POSIX</code>.

blocks|key|1510818|text|负数可能会增加一些人们需要注意的怪癖。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1510819|printf-style方法给出了正确的数字，但它们可能会导致一些奇怪的显示。我们发现这个方法(在我看来很愚蠢)放入一个-符号，不管它应该还是不应该。例如，-0.01四舍五入到小数点后一位将返回-0.0，而不仅仅是0。如果您要使用printf样式的方法，并且您知道不需要小数，请使用%25d而不是%25f+(当您需要小数时，就是显示不稳定的时候)。|offset|length|style|CODE|1510820|虽然它是正确的，并且对于数学来说没什么大不了的，但对于显示来说，它显示类似于"-0.0“的内容看起来很奇怪。|1510821|对于int方法，负数可以改变您想要的结果(尽管可以使用一些参数，但它们是正确的)。|1510822|int+%2B+0.5会导致-negative数字的真正问题，除非你希望它以这种方式工作，但我想大多数人都不会。-0.9可能会四舍五入为-1，而不是0。如果你知道你想让负数成为一个上限而不是一个下限，那么你可以用一行代码来实现它，否则，你可能想要使用int方法，只做一点小小的修改(这显然只对取回整数有效：|1510823|my+$var+=+-9.1;
my+$tmpRounded+=+int(+abs($var)+%2B+0.5));
my+$finalRounded+=+$var+>=+0+?+0+%2B+$tmpRounded+:+0+-+$tmpRounded;|code-block|syntax|javascript|1510824|entityMap^0|0|0|6|1O|1|37|6|3X|2|42|2|0|0|0|0|9|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@$D|W|E|X|F|G]|$D|Y|E|Z|F|G]|$D|10|E|11|F|G]|$D|12|E|13|F|G]|$D|14|E|15|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|16|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|17|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|18|8|@$D|19|E|1A|F|G]]|9|@]|A|$]]|$1|N|3|O|5|P|7|1B|8|@]|9|@]|A|$Q|R]]|$1|S|3|-4|5|6|7|1C|8|@]|9|@]|A|$]]]|T|$]]

Negative numbers can add some quirks that people need to be aware of.

<code>printf</code>-style approaches give us correct numbers, but they can result in some odd displays. We have discovered that this method (in my opinion, stupidly) puts in a <code>-</code> sign whether or not it should or shouldn't. For example, -0.01 rounded to one decimal place returns a -0.0, rather than just 0. If you are going to do the <code>printf</code> style approach, and you know you want no decimal, use <code>%d</code> and not <code>%f</code> (when you need decimals, it's when the display gets wonky).

While it's correct and for math no big deal, for display it just looks weird showing something like "-0.0".

For the int method, negative numbers can change what you want as a result (though there are some arguments that can be made they are correct).

The <code>int + 0.5</code> causes real issues with -negative numbers, unless you want it to work that way, but I imagine most people don't. -0.9 should probably round to -1, not 0. If you know that you want negative to be a ceiling rather than a floor then you can do it in one-liner, otherwise, you might want to use the int method with a minor modification (this obviously only works to get back whole numbers:

<pre><code>my $var = -9.1;
my $tmpRounded = int( abs($var) + 0.5));
my $finalRounded = $var &gt;= 0 ? 0 + $tmpRounded : 0 - $tmpRounded;
</code></pre>

blocks|key|1725986|text|我对sprintf的解决方案|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1725987|if+($value+=~+m/\d\..*5$/){
++++$format+=~+/.*(\d)f$/;
++++if+(defined+$1){
+++++++my+$coef+=+"0."+.+"0"+x+$1+.+"05";++++
++++++++++++$value+=+$value+%2B+$coef;++++
++++}
}

$value+=+sprintf(+"$format",+$value+);|code-block|syntax|javascript|1725988|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

My solution for sprintf

<pre><code>if ($value =~ m/\d\..*5$/){
 $format =~ /.*(\d)f$/;
 if (defined $1){
 my $coef = "0." . "0" x $1 . "05"; 
 $value = $value + $coef; 
 }
}

$value = sprintf( "$format", $value );
</code></pre>

blocks|key|1511024|text|如果你只关心从一个整数浮点数(即12347.9999或54321.0001)中获取一个整数值，这种方法(从上面借用和修改)将会起到作用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1511025|my+$rounded+=+floor($float+%2B+0.1);+|code-block|syntax|javascript|1511026|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If you are only concerned with getting an integer value out of a whole floating point number (i.e. 12347.9999 or 54321.0001), this approach (borrowed and modified from above) will do the trick:

<pre><code>my $rounded = floor($float + 0.1); 
</code></pre>

blocks|key|1511120|text|使用Math::BigFloat，您可以执行以下操作：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1511121|use+Math::BigFloat;

print+Math::BigFloat->new(1.2)->bfround(1);+##+1
print+Math::BigFloat->new(1.7)->bfround(1);+##+2|code-block|syntax|javascript|1511122|这可以包装在一个子例程中|1511123|use+Math::BigFloat;

sub+round+{
++Math::BigFloat->new(shift)->bfround(1);
}

print+round(1.2);+##+1
print+round(1.7);+##+2|1511124|entityMap|0|LINK|mutability|MUTABLE|url|https://perldoc.perl.org/Math::BigFloat^0|2|E|2|E|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@$9|Z|A|10|1|11]]|E|$]]|$1|F|3|G|5|H|7|12|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|13|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|14|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|15|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]]]

Using <a href="https://perldoc.perl.org/Math::BigFloat" rel="nofollow noreferrer"><code>Math::BigFloat</code></a> you can do something like this:
<pre><code>use Math::BigFloat;

print Math::BigFloat-&gt;new(1.2)-&gt;bfround(1); ## 1
print Math::BigFloat-&gt;new(1.7)-&gt;bfround(1); ## 2
</code></pre>
This can be wrapped in a subroutine
<pre><code>use Math::BigFloat;

sub round {
 Math::BigFloat-&gt;new(shift)-&gt;bfround(1);
}

print round(1.2); ## 1
print round(1.7); ## 2
</code></pre>

blocks|key|1511074|text|许多专家建议您编写自己的舍入例程，因为随您的语言提供的“罐头”版本可能不够精确，或者包含错误。然而，我想他们谈论的是许多小数位，而不仅仅是一、二或三位。考虑到这一点，这里是我的解决方案(尽管不完全像我需要的那样显示美元-尽管过程没有太大不同)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1511075|sub+asDollars($)+{
++my+($cost)+=+@_;
++my+$rv+=+0;

++my+$negative+=+0;
++if+($cost+=~+/%5E-/)+{
++++$negative+=+1;
++++$cost+=~+s/%5E-//;
++}

++my+@cost+=+split(/\./,+$cost);

++#+let's+get+the+first+3+digits+of+$cost[1]
++my+($digit1,+$digit2,+$digit3)+=+split("",+$cost[1]);
++#+now,+is+$digit3+>=+5?
++#+if+yes,+plus+one+to+$digit2.
++#+is+$digit2+>+9+now?
++#+if+yes,+$digit2+=+0,+$digit1%2B%2B
++#+is+$digit1+>+9+now??
++#+if+yes,+$digit1+=+0,+$cost[0]%2B%2B
++if+($digit3+>=+5)+{
++++$digit3+=+0;
++++$digit2%2B%2B;
++++if+($digit2+>+9)+{
++++++$digit2+=+0;
++++++$digit1%2B%2B;
++++++if+($digit1+>+9)+{
++++++++$digit1+=+0;
++++++++$cost[0]%2B%2B;
++++++}
++++}
++}
++$cost[1]+=+$digit1+.+$digit2;
++if+($digit1+ne+"0"+and+$cost[1]+<+10)+{+$cost[1]+.=+"0";+}

++#+and+pretty+up+the+left+of+decimal
++if+($cost[0]+>+999)+{+$cost[0]+=+commafied($cost[0]);+}

++$rv+=+join(".",+@cost);

++if+($negative)+{+$rv+=+"-"+.+$rv;+}

++return+$rv;
}

sub+commafied($)+{
++#*
++#+to+insert+commas+before+every+3rd+number+(from+the+right)
++#+positive+or+negative+numbers
++#*
++my+($num)+=+@_;+#+the+number+to+insert+commas+into!

++my+$negative+=+0;
++if+($num+=~+/%5E-/)+{
++++$negative+=+1;
++++$num+=~+s/%5E-//;
++}
++$num+=~+s/%5E(0)*//;+#+strip+LEADING+zeros+from+given+number!
++$num+=~+s/0/-/g;+#+convert+zeros+to+dashes+because+...+computers!

++if+($num)+{
++++my+@digits+=+reverse+split("",+$num);
++++$num+=+"";

++++for+(my+$i+=+0;+$i+<+@digits;+$i+%2B=+3)+{
++++++$num+.=+$digits[$i];
++++++if+($digits[$i%2B1])+{+$num+.=+$digits[$i%2B1];+}
++++++if+($digits[$i%2B2])+{+$num+.=+$digits[$i%2B2];+}
++++++if+($i+<+(@digits+-+3))+{+$num+.=+",";+}
++++++if+($i+>=+@digits)+{+last;+}
++++}

++++#$num+=~+s/,$//;
++++$num+=+join("",+reverse+split("",+$num));
++++$num+=~+s/-/0/g;
++}

++if+($negative)+{+$num+=+"-"+.+$num;+}

++return+$num;+#+a+number+with+commas+added
++#usage:+my+$prettyNum+=+commafied(1234567890);
}|code-block|syntax|javascript|1511076|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

loads of reading documentation on how to round numbers, many experts suggest writing your own rounding routines, as the 'canned' version provided with your language may not be precise enough, or contain errors. i imagine, however, they're talking many decimal places not just one, two, or three. with that in mind, here is my solution (although not EXACTLY as requested as my needs are to display dollars - the process is not much different, though). 

<pre><code>sub asDollars($) {
 my ($cost) = @_;
 my $rv = 0;

 my $negative = 0;
 if ($cost =~ /^-/) {
 $negative = 1;
 $cost =~ s/^-//;
 }

 my @cost = split(/\./, $cost);

 # let's get the first 3 digits of $cost[1]
 my ($digit1, $digit2, $digit3) = split("", $cost[1]);
 # now, is $digit3 &gt;= 5?
 # if yes, plus one to $digit2.
 # is $digit2 &gt; 9 now?
 # if yes, $digit2 = 0, $digit1++
 # is $digit1 &gt; 9 now??
 # if yes, $digit1 = 0, $cost[0]++
 if ($digit3 &gt;= 5) {
 $digit3 = 0;
 $digit2++;
 if ($digit2 &gt; 9) {
 $digit2 = 0;
 $digit1++;
 if ($digit1 &gt; 9) {
 $digit1 = 0;
 $cost[0]++;
 }
 }
 }
 $cost[1] = $digit1 . $digit2;
 if ($digit1 ne "0" and $cost[1] &lt; 10) { $cost[1] .= "0"; }

 # and pretty up the left of decimal
 if ($cost[0] &gt; 999) { $cost[0] = commafied($cost[0]); }

 $rv = join(".", @cost);

 if ($negative) { $rv = "-" . $rv; }

 return $rv;
}

sub commafied($) {
 #*
 # to insert commas before every 3rd number (from the right)
 # positive or negative numbers
 #*
 my ($num) = @_; # the number to insert commas into!

 my $negative = 0;
 if ($num =~ /^-/) {
 $negative = 1;
 $num =~ s/^-//;
 }
 $num =~ s/^(0)*//; # strip LEADING zeros from given number!
 $num =~ s/0/-/g; # convert zeros to dashes because ... computers!

 if ($num) {
 my @digits = reverse split("", $num);
 $num = "";

 for (my $i = 0; $i &lt; @digits; $i += 3) {
 $num .= $digits[$i];
 if ($digits[$i+1]) { $num .= $digits[$i+1]; }
 if ($digits[$i+2]) { $num .= $digits[$i+2]; }
 if ($i &lt; (@digits - 3)) { $num .= ","; }
 if ($i &gt;= @digits) { last; }
 }

 #$num =~ s/,$//;
 $num = join("", reverse split("", $num));
 $num =~ s/-/0/g;
 }

 if ($negative) { $num = "-" . $num; }

 return $num; # a number with commas added
 #usage: my $prettyNum = commafied(1234567890);
}
</code></pre>

blocks|key|1725827|text|cat+table+%7C
++perl+-ne+'/\d%2B\s%2B(\d%2B)\s%2B(\S%2B)/+&&+print+"".**int**(log($1)/log(2))."\t$2\n";'+|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1725828|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>cat table |
 perl -ne '/\d+\s+(\d+)\s+(\S+)/ &amp;&amp; print "".**int**(log($1)/log(2))."\t$2\n";' 
</code></pre>

How can I round a decimal number (floating point) to the nearest integer? 

e.g.

<pre><code>1.2 = 1
1.7 = 2
</code></pre>

How do you round a floating point number in Perl?

如何将十进制数(浮点数)舍入为最接近的整数？例如：1.2 = 11.7 = 2

问在Perl中如何对浮点数进行舍入？
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回答 10

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问在Perl中如何对浮点数进行舍入？
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