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printf

Description

The printf of String for PHP outputs a formatted string.

Syntax

printf(
    string $format,
    mixed ...$values
): int

Parameters

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.

Argnum

An integer followed by a dollar sign $, to specify which number argument to treat in the conversion.

Flags
FlagDescription
-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.
0Only left-pads numbers with zeros. With s specifiers this can also right-pad with zeros.
'(char)Pads the result with the character (char).
Width

An integer that says how many characters (minimum) this conversion should result in.

Precision

A period . followed by an integer who's meaning depends on the specifier:

For e, E, f and F specifiers: this is the number of digits to be printed after the decimal point (by default, this is 6).

For g and G specifiers: this is the maximum number of significant digits to be printed.

For 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.

Specifier
SpecifierDescription
%A literal percent character. No argument is required.
bThe argument is treated as an integer and presented as a binary number.
cThe argument is treated as an integer and presented as the character with that ASCII.
dThe argument is treated as an integer and presented as a (signed) decimal number.
eThe 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).
ELike the e specifier but uses uppercase letter (e.g. 1.2E+2).
fThe argument is treated as a float and presented as a floating-point number (locale aware).
FThe argument is treated as a float and presented as a floating-point number (non-locale aware).
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.
GLike the g specifier but uses E and f.
oThe argument is treated as an integer and presented as an octal number.
sThe argument is treated and presented as a string.
uThe argument is treated as an integer and presented as an unsigned decimal number.
xThe argument is treated as an integer and presented as a hexadecimal number (with lowercase letters).
XThe argument is treated as an integer and presented as a hexadecimal number (with uppercase letters).

WARNING: The c type specifier ignores padding and width

WARNING: 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:

TypeSpecifiers
strings
intd, u, c, o, x, X, b
floate, E, f, F, g, G, h, H

values

Return

Returns the length of the outputted string.

Examples

1 · format values · single

<?

$format = "%s";
$values = "Hello";

printf($format, $values);

Hello

2 · format values · multiple

<?

$format = "%1s %2s";
$values1 = "Hello";
$values2 = "World!";

printf($format, $values1, $values2);

Hello World!

3 · justification

<?

$values = "justification";

printf("[%-20s]\n", $values);
printf("[%20s]\n", $values);

[justification       ]
[       justification]

4

<?

$values1 = -123456789;
$values2 = 123456789;

printf("%d\n", $values1);
printf("%d\n", $values2);
printf("%+d\n", $values1);
printf("%+d\n", $values2);
printf("%u\n", $values1);
printf("%u\n", $values2);

-123456789
123456789
-123456789
+123456789
18446744073586094827
123456789

5 · padding

<?

$values = "padding";

printf("[%20s]\n", $values);
printf("[%020s]\n", $values);
printf("[%'.20s]\n", $values);
printf("[%'p20s]\n", $values);

[             padding]
[0000000000000padding]
[.............padding]
[ppppppppppppppadding]

6 · width

<?

$values = "width";

printf("[%10s]\n", $values);
printf("[%20s]\n", $values);
printf("[%30s]\n", $values);
printf("[%40s]\n", $values);

[     width]
[               width]
[                         width]
[                                   width]

7

<?

$values = 0.123456789;

printf("%.2e\n", $values);
printf("%.4e\n", $values);
printf("%e\n", $values);
printf("%.8e\n", $values);
printf("%.2E\n", $values);
printf("%.4E\n", $values);
printf("%E\n", $values);
printf("%.8E\n", $values);
printf("%.2f\n", $values);
printf("%.4f\n", $values);
printf("%f\n", $values);
printf("%.8f\n", $values);
printf("%.2F\n", $values);
printf("%.4F\n", $values);
printf("%F\n", $values);
printf("%.8F\n", $values);

1.23e-1
1.2346e-1
1.234568e-1
1.23456789e-1
1.23E-1
1.2346E-1
1.234568E-1
1.23456789E-1
0.12
0.1235
0.123457
0.12345679
0.12
0.1235
0.123457
0.12345679

8

<?

$values = 123456789;

printf("%.2g\n", $values);
printf("%.4g\n", $values);
printf("%g\n", $values);
printf("%.8g\n", $values);
printf("%.2G\n", $values);
printf("%.4G\n", $values);
printf("%G\n", $values);
printf("%.8G\n", $values);

1.2e+8
1.235e+8
1.23457e+8
1.2345679e+8
1.2E+8
1.235E+8
1.23457E+8
1.2345679E+8

9 · precision

<?

$values = "precision";

printf("%.3s\n", $values);
printf("%.4s\n", $values);
printf("%.5s\n", $values);
printf("%.6s\n", $values);

pre
prec
preci
precis

10 · character

<?

$format = "%%c = %c";
$values = 65;

printf($format, $values);

%c = A

11

<?

$array =
[
    "b",
    "d",
    "e","E",
    "f","F",
    "g","G",
    "o",
    "s",
    "u",
    "x","X"
];
$values = 123456789;

foreach($array as $value)
{
    $format = "%%$value = %$value\n";

    printf($format, $values);
}

%b = 111010110111100110100010101
%d = 123456789
%e = 1.234568e+8
%E = 1.234568E+8
%f = 123456789.000000
%F = 123456789.000000
%g = 1.23457e+8
%G = 1.23457E+8
%o = 726746425
%s = 123456789
%u = 123456789
%x = 75bcd15
%X = 75BCD15

12 · return

<?

$format = "%s";
$values = "Hello";

$return = printf($format, $values);

echo PHP_EOL . $return;

Hello
5