PHP printf() Function
The PHP printf() function produces output according to the specified format. If format includes format specifiers (sub-sequences beginning with %), the additional arguments following format are formatted and inserted in the resulting string replacing their respective specifiers.
After the format parameter, the function expects additional arguments at least as many as the number of format specifiers in the format string.
Syntax
printf(format, arguments)
Parameters
format |
Additional format values can be placed between the % and the specifier (e.g. %.3f). The possible values which can be placed in between are:
Note: If multiple additional format values are provided, they must be in %[flags][width][.precision]specifier order. | ||||||||||||||||||||||||||||||||||||
arguments |
Optional. Depending on the format string, a sequence of additional arguments should be passed in the function, each containing a value to replace a format specifiers in the format string. Number of arguments should be at least equal to the number of format specifiers in the format string. Additional arguments will be ignored by this function. |
Return Value
Returns the length of the outputted string.
Example: different specifiers
In the example below, a given variable is outputted using different specifier.
<?php
$n = 5000;
$u = -5000;
$c = 66; // ASCII 66 is 'B'
//%% is used to print '%' character
printf("%%b = %b\n", $n); //binary
printf("%%c = %c\n", $c); //ASCII character
printf("%%d = %d\n", $n); //integer
printf("%%e = %e\n", $n); //scientific notation
printf("%%u = %u\n", $n); //unsigned integer (+ve number)
printf("%%u = %u\n", $u); //unsigned integer (-ve number)
printf("%%f = %f\n", $n); //floating point
printf("%%o = %o\n", $n); //octal
printf("%%s = %s\n", $n); //string
printf("%%x = %x\n", $n); //hexadecimal (lowercase)
printf("%%X = %X\n", $n); //hexadecimal (uppercase)
printf("%%+d = %+d\n", $n); //sign specifier (+ve number)
printf("%%+d = %+d\n", $u); //sign specifier (-ve number)
?>
The output of the above code will be:
%b = 1001110001000 %c = B %d = 5000 %e = 5.000000e+3 %u = 5000 %u = 18446744073709546616 %f = 5000.000000 %o = 11610 %s = 5000 %x = 1388 %X = 1388 %+d = +5000 %+d = -5000
Example: using multiple % signs
In the example below, multiple % signs are used to place multiple additional arguments in the outputted string.
<?php
$name = 'John';
$age = 25;
printf("%s is %d years old.\n", $name, $age);
//using precision format
printf("%s is %.2f years old.\n", $name, $age);
?>
The output of the above code will be:
John is 25 years old. John is 25.00 years old.
Example: output a date string
In the example below, this function is used to output formatted date string.
<?php
$year = 2015;
$month = 5;
$day = 1;
//each format specifier specifies padding
//with 0 and width of the field
printf("%04d-%02d-%02d", $year, $month, $day);
?>
The output of the above code will be:
2015-05-01
Example: string specifiers
Consider one more example to see how to use string specifiers with a given string.
<?php
$x = 'catfish';
$y = 'many catfishes';
printf("[%s]\n", $x); //standard string output
printf("[%10s]\n", $x); //right-justification with spaces
printf("[%-10s]\n", $x); //left-justification with spaces
printf("[%010s]\n", $x); //zero-padding works on strings too
printf("[%'#10s]\n", $x); //using custom padding character '#'
printf("[%10.8s]\n", $y); //right-justification (8 characters cutoff)
printf("[%-10.8s]\n", $y); //left-justification (8 characters cutoff)
?>
The output of the above code will be:
[catfish] [ catfish] [catfish ] [000catfish] [###catfish] [ many cat] [many cat ]
❮ PHP String Reference
