(PHP 4, PHP 5, PHP 7)
printf — Output a formatted string
format
The format string is composed of zero or more directives:
ordinary characters (excluding %) that are
copied directly to the result and conversion
specifications, each of which results in fetching its
own parameter.
A conversion specification follows this prototype:
%[argnum$][flags][width][.precision]specifier.
An integer followed by a dollar sign $,
to specify which number argument to treat in the conversion.
| Flag | Description |
|---|---|
- |
Left-justify within the given field width; Right justification is the default |
+ |
Prefix positive numbers with a plus sign
+; Default only negative
are prefixed with a negative sign.
|
(space) |
Pads the result with spaces. This is the default. |
0 |
Only left-pads numbers with zeros.
With s specifiers this can
also right-pad with zeros.
|
'(char) |
Pads the result with the character (char). |
An integer that says how many characters (minimum) this conversion should result in.
A period . followed by an integer
who's meaning depends on the specifier:
e, E,
f and F
specifiers: this is the number of digits to be printed
after the decimal point (by default, this is 6).
g and G
specifiers: this is the maximum number of significant
digits to be printed.
s specifier: it acts as a cutoff point,
setting a maximum character limit to the string.
Note: If the period is specified without an explicit value for precision, 0 is assumed.
Note: Attempting to use a position specifier greater than
PHP_INT_MAXwill generate warnings.
| Specifier | Description |
|---|---|
% |
A literal percent character. No argument is required. |
b |
The argument is treated as an integer and presented as a binary number. |
c |
The argument is treated as an integer and presented as the character with that ASCII. |
d |
The argument is treated as an integer and presented as a (signed) decimal number. |
e |
The argument is treated as scientific notation (e.g. 1.2e+2). The precision specifier stands for the number of digits after the decimal point since PHP 5.2.1. In earlier versions, it was taken as number of significant digits (one less). |
E |
Like the e specifier but uses
uppercase letter (e.g. 1.2E+2).
|
f |
The argument is treated as a float and presented as a floating-point number (locale aware). |
F |
The argument is treated as a float and presented as a floating-point number (non-locale aware). Available as of PHP 5.0.3. |
g |
General format. Let P equal the precision if nonzero, 6 if the precision is omitted, or 1 if the precision is zero. Then, if a conversion with style E would have an exponent of X: If P > X ≥ −4, the conversion is with style f and precision P − (X + 1). Otherwise, the conversion is with style e and precision P − 1. |
G |
Like the g specifier but uses
E and f.
|
o |
The argument is treated as an integer and presented as an octal number. |
s |
The argument is treated and presented as a string. |
u |
The argument is treated as an integer and presented as an unsigned decimal number. |
x |
The argument is treated as an integer and presented as a hexadecimal number (with lowercase letters). |
X |
The argument is treated as an integer and presented as a hexadecimal number (with uppercase letters). |
The c type specifier ignores padding and width
Attempting to use a combination of the string and width specifiers with character sets that require more than one byte per character may result in unexpected results
Variables will be co-erced to a suitable type for the specifier:
| Type | Specifiers |
|---|---|
string |
s |
integer |
d,
u,
c,
o,
x,
X,
b
|
double |
g,
G,
e,
E,
f,
F
|
...
Returns the length of the outputted string.
Example #1 printf(): various examples
<?php
$n = 43951789;
$u = -43951789;
$c = 65; // ASCII 65 is 'A'
// notice the double %%, this prints a literal '%' character
printf("%%b = '%b'\n", $n); // binary representation
printf("%%c = '%c'\n", $c); // print the ascii character, same as chr() function
printf("%%d = '%d'\n", $n); // standard integer representation
printf("%%e = '%e'\n", $n); // scientific notation
printf("%%u = '%u'\n", $n); // unsigned integer representation of a positive integer
printf("%%u = '%u'\n", $u); // unsigned integer representation of a negative integer
printf("%%f = '%f'\n", $n); // floating point representation
printf("%%o = '%o'\n", $n); // octal representation
printf("%%s = '%s'\n", $n); // string representation
printf("%%x = '%x'\n", $n); // hexadecimal representation (lower-case)
printf("%%X = '%X'\n", $n); // hexadecimal representation (upper-case)
printf("%%+d = '%+d'\n", $n); // sign specifier on a positive integer
printf("%%+d = '%+d'\n", $u); // sign specifier on a negative integer
?>
The above example will output:
%b = '10100111101010011010101101' %c = 'A' %d = '43951789' %e = '4.39518e+7' %u = '43951789' %u = '4251015507' %f = '43951789.000000' %o = '247523255' %s = '43951789' %x = '29ea6ad' %X = '29EA6AD' %+d = '+43951789' %+d = '-43951789'
Example #2 printf(): string specifiers
<?php
$s = 'monkey';
$t = 'many monkeys';
printf("[%s]\n", $s); // standard string output
printf("[%10s]\n", $s); // right-justification with spaces
printf("[%-10s]\n", $s); // left-justification with spaces
printf("[%010s]\n", $s); // zero-padding works on strings too
printf("[%'#10s]\n", $s); // use the custom padding character '#'
printf("[%10.9s]\n", $t); // right-justification but with a cutoff of 8 characters
printf("[%-10.9s]\n", $t); // left-justification but with a cutoff of 8 characters
?>
The above example will output:
[monkey] [ monkey] [monkey ] [0000monkey] [####monkey] [ many monk] [many monk ]