Rounding numbers with PHP

I have previously looked at rounding numbers with MySQL and Javascript and in this post look at rounding numbers with PHP using the round() ceil() floor() number_format() and s/printf() functions.

round()

The round() function rounds the number passed in to the specified number of decimal places. If the decimal places is a negative number then the numbers to the left of the decimal place are rounded. If the decimal places parameter is not passed in then it defaults to zero and will round as an integer. 5 is round up and < 5 is rounded down.

echo round(153.751, 2);  // 153.75
echo round(153.751, 1);  // 153.8
echo round(153.751);     // 154
echo round(153.751, -1); // 150
echo round(153.751, -2); // 200

From PHP 5.3.0 round() accepts a 3rd parameter can be passed which specifys the rounding mode and is one of PHP_ROUND_HALF_UP, PHP_ROUND_HALF_DOWN, PHP_ROUND_HALF_EVEN, or PHP_ROUND_HALF_ODD. It defaults to PHP_ROUND_HALF_UP to maintain backward compatibility.

ceil()

The ceil() function rounds up to the nearest integer (ceil = ceiling). There is no argument for precision so it will always round up to the nearest integer. If the number is already an integer then the value returned will remain the same.

echo ceil(153.251); // 154
echo ceil(153.751); // 154
echo ceil(-153.251); // -153
echo ceil(-153.751); // -153

floor()

The floor() functuon works the same was as ceil() but always rounding down to the nearest integer. Some examples:

echo floor(153.251); // 153
echo floor(153.751); // 153
echo floor(-153.251); // -154
echo floor(-153.751); // -154

number_format()

The PHP number_format() function is used for formatting numbers with decimal places and thousands separators, but it also rounds numbers if there are more decimal places in the original number than required. As with round() it will round up on 5 and down on < 5.

echo number_format(153.751); // 154
echo number_format(153.751, 1); // 153.8
echo number_format(153.751, 2); // 153.75

printf() and sprintf()

The printf() and sprintf() functions are also for formatting and again will round numbers as well. printf() outputs the value to standard output whereas sprintf() returns it as a value.

printf("%0.2f", 153.751); // 153.75
printf("%0.1f", 153.751); // 153.8
printf("%d", 153.751); // 153

Related posts:

• Rounding numbers with MySQL
• Rounding numbers with Javascript

PHP: Displays month, day and year

<?php
$date = getdate( );
printf('%s %d, %d',$date['month'],$date['mday'],$date['year']);
?>

PHP: Display A to Z links on your site

<?php
for ($i = 65 ; $i < 91 ; $i++)
{
printf ('<a href = "%s?mylink=%s">%s</a> ', $PHP_SELF, chr($i), chr($i));
}
?>

printf in PHP

PHP printf() function is utilized to print formatted string from one or more arguments.

Syntax:

printf(format,arg1,arg2,arg++)
format : Required. Defines the string and how to format the variables in it..

arg1 : Required. The argument to be added as the first %-sign.

arg2 : Optional. The argument to be added at the second %-sign

arg++ : Optional. The argument to be added at the third, fourth etc. %-sign

Note : If there are more % signs than arguments, you must use placeholders.
Note : The only difference between printf() and sprintf() is that printf() sends the resulting string directly to the output whereas sprintf() returns the result string as its value.

Tip : Related functions: fprintf(), sprintf(), vfprintf(), vprintf() and vsprintf().

Example:

<?php
$str_name = "Morning!";
$my_name = "Jack.";
$day_num = 100;
printf("Good %s My name is %s It is day number %u",$str_name,$my_name,$day_num);
?>
Output will be:
Good Morning! My name is Jack. It is day number 100