PHP printf() Function
PHP String Reference
Example
Output a formatted string:
<?php
$number = 9;
$str = "Beijing";
printf("There are %u
million bicycles in %s.",$number,$str);
?>
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Definition and Usage
The printf() function outputs a formatted string.
The arg1, arg2, ++ parameters will be inserted at percent (%)
signs in the main string. This function works "step-by-step". At the first % sign,
arg1 is inserted, at the second % sign, arg2 is inserted, etc.
Note: If there are more % signs than arguments, you must use placeholders. A placeholder is
inserted after the % sign,
and consists of the argument- number and "\$". See example two.
Tip: Related functions: sprintf(),
vprintf(),
vsprintf(),
fprintf() and
vfprintf()
Syntax
printf(format,arg1,arg2,arg++)
Parameter |
Description |
format |
Required. Specifies the string and how to format the
variables in it. Possible format values:
- %% - Returns a percent sign
- %b - Binary number
- %c - The character according to the ASCII value
- %d - Signed decimal number (negative, zero or positive)
- %e - Scientific notation using a lowercase (e.g. 1.2e+2)
- %E - Scientific notation using a uppercase (e.g. 1.2E+2)
- %u - Unsigned decimal number (equal to or greather than zero)
- %f - Floating-point number (local settings aware)
- %F - Floating-point number (not local settings
aware)
- %g - shorter of %e and %f
- %G - shorter of %E and %f
- %o - Octal number
- %s - String
- %x - Hexadecimal number (lowercase letters)
- %X - Hexadecimal number (uppercase letters)
Additional format values. These are placed between the % and the letter
(example %.2f):
- + (Forces both + and - in front of numbers. By
default, only negative numbers are marked)
- ' (Specifies what to use as padding. Default is space. Must be used
together with the width specifier.
Example: %'x20s (this uses "x" as padding)
- - (Left-justifies the variable value)
- [0-9] (Specifies the minimum width held of to the variable value)
- .[0-9] (Specifies the number of decimal digits or maximum
string length)
Note: If multiple additional format values are used, they must be in the same
order as above. |
arg1 |
Required. The argument to be inserted at
the first %-sign in the format string |
arg2 |
Optional. The argument to be inserted
at the second %-sign in the format string |
arg++ |
Optional. The argument to be inserted
at the third, fourth, etc. %-sign in the format string |
Technical Details
Return Value: |
Returns the length of the outputted string |
PHP Version: |
4+ |
More Examples
Example 1
Using the format value %f:
<?php
$number = 123;
printf("%f",$number);
?>
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Example 2
Use of placeholders:
<?php
$number = 123;
printf("With 2 decimals: %1\$.2f
<br>With no decimals: %1\$u",$number);
?>
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Example 3
A demonstration of all possible format values:
<?php
$num1 = 123456789;
$num2 = -123456789;
$char = 50; // The
ASCII Character 50 is 2
// Note: The format value "%%" returns a
percent sign
printf("%%b = %b <br>",$num1); // Binary number
printf("%%c
= %c <br>",$char); // The ASCII Character
printf("%%d = %d <br>",$num1);
// Signed decimal number
printf("%%d = %d <br>",$num2); // Signed decimal
number
printf("%%e = %e <br>",$num1); // Scientific notation (lowercase)
printf("%%E = %E <br>",$num1); // Scientific notation (uppercase)
printf("%%u
= %u <br>",$num1); // Unsigned decimal number (positive)
printf("%%u = %u
<br>",$num2); // Unsigned decimal number (negative)
printf("%%f = %f <br>",$num1);
// Floating-point number (local settings aware)
printf("%%F = %F <br>",$num1);
// Floating-point number (not local settings aware)
printf("%%g = %g <br>",$num1);
// Shorter of %e and %f
printf("%%G = %G <br>",$num1); // Shorter of %E
and %f
printf("%%o = %o <br>",$num1); // Octal number
printf("%%s = %s
<br>",$num1); // String
printf("%%x = %x <br>",$num1); // Hexadecimal
number (lowercase)
printf("%%X = %X <br>",$num1); // Hexadecimal number
(uppercase)
printf("%%+d = %+d <br>",$num1); // Sign specifier (positive)
printf("%%+d = %+d <br>",$num2); // Sign specifier (negative)
?>
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Example 4
A demonstration of string specifiers:
<?php
$str1 = "Hello";
$str2 = "Hello world!";
printf("[%s]<br>",$str1);
printf("[%8s]<br>",$str1);
printf("[%-8s]<br>",$str1);
printf("[%08s]<br>",$str1);
printf("[%'*8s]<br>",$str1);
printf("[%8.8s]<br>",$str2);
?>
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