Be careful:
printf ("(9.95 * 100) = %d \n", (9.95 * 100));
'994'
First %d converts a float to an int by truncation.
Second floats are notorious for tiny little rounding errors.
printf
(PHP 4, PHP 5, PHP 7, PHP 8)
printf — 输出格式化字符串
参数
-
format -
format 字符串通常由零或多个指令组成：普通字符（不包含
%）——直接复制到结果，转换规范——获取每个参数的结果。转换规范遵循此原型：
%[argnum$][flags][width][.precision]specifier.Argnum
整数后跟美元符号
$，用于指定转换中要处理的参数数量。标志 标志 说明 -在指定字段宽度时左对齐，默认右对齐 +正数的加号 +前缀，默认负数的前缀是负号。空格填充结果。这是默认设置。 0仅用 0 进行左侧数字填充。使用 s标志符可以右侧填充。'(char)用字符（char）填充结果。 Width
要么是整数，表示转换结果应该有多少个字符（最少），要么是
*。如果使用*，那么宽度将作为额外的整数值提供，位于格式化符号之前。Precision
小数点
.，可选的后跟整数或者*，其含义取决于格式化符号：-
e、E、f、F标志符：小数点后需要打印的位数（默认是 6）。 -
g、G、h、H标志符：这是要打印的最大有效位数。 -
s标志符：充当分界点，为字符串设置最大字符限制。
注意: 如果小数点没有明确的精度值，则假设是 0。如果使用
*，则精度将作为额外的整数值提供，位于格式化符号之前。标志符 标志符 说明 %字面意思的百分号字符。不需要参数。 b参数视为整数并以二进制数字呈现。 c参数视为整数并以 ASCII 字符呈现。 d参数视为整数并以（有符号）十进制数字呈现。 e参数当做科学符号处理（例如 1.2e+2）。 E与 e标志符相同，但使用大写字母（例如 1.2E+2）。f参数当做浮点数处理且作为浮点数呈现（locale aware）。 F参数当做浮点数处理且作为浮点数呈现（non-locale aware）。 g通用格式。
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 gspecifier but usesEandf.hLike the gspecifier but usesF. Available as of PHP 8.0.0.HLike the gspecifier but usesEandF. Available as of PHP 8.0.0.o参数视为整数并以八进制数字来呈现。 s参数视为字符串来呈现。 u参数视为整数并以无符号十进制数字呈现。 x参数视为整数并作为十六进制数字呈现（带小写字母）。 X参数视为整数并作为十六进制数字呈现（带大写字母）。 警告c类型标志符忽略填充和宽度警告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
变量将会强制转换为适合标志符的类型：
类型处理 类型 标志符 string sint d,u,c,o,x,X,bfloat e,E,f,F,g,G,h,H -
-
values -
返回值
返回输出字符串的长度。
错误／异常
从 PHP 8.0.0 开始，如果参数个数为零，将抛出 ValueError。在 PHP 8.0.0 之前，会发出 E_WARNING。
从 PHP 8.0.0 开始，如果 [width] 小于零或大于 PHP_INT_MAX，则会抛出
ValueError。在 PHP 8.0.0 之前，会发出 E_WARNING。
从 PHP 8.0.0 开始，如果 [precision] 小于零或大于 PHP_INT_MAX，则会抛出
ValueError。在 PHP 8.0.0 之前，会发出 E_WARNING。
从 PHP 8.0.0 开始，当传递的参数少于所需的参数时会抛出 ArgumentCountError。在 PHP 8.0.0 之前，返回 false 并发出 E_WARNING。
更新日志
| 版本 | 说明 |
|---|---|
| 8.0.0 |
此函数失败时不再返回 false。
|
| 8.0.0 |
如果参数个数为零则抛出 ValueError；以前该函数则会发出 E_WARNING。
|
| 8.0.0 |
如果 [width] 小于零或大于 PHP_INT_MAX，则抛出 ValueError；以前该函数则会发出 E_WARNING。
|
| 8.0.0 |
如果 [precision] 小于零或大于 PHP_INT_MAX，则抛出 ValueError；以前该函数则会发出 E_WARNING。
|
| 8.0.0 |
当传递的参数少于所需的参数时抛出 ArgumentCountError；以前该函数则会发出 E_WARNING。
|
示例
示例 #1 printf()：多种 format 格式的示例
<?php
$n = 43951789;
$u = -43951789;
$c = 65; // ASCII 65 is 'A'
// 注意两个 %% 的情况，这会打印一个字面上的 '%' 字符
printf("%%b = '%b'\n", $n); // 二进制表示
printf("%%c = '%c'\n", $c); // 打印 ascii 字符，与 chr() 函数相同
printf("%%d = '%d'\n", $n); // 标准整数表示
printf("%%e = '%e'\n", $n); // 科学计数法
printf("%%u = '%u'\n", $n); // 无符号正整数表示
printf("%%u = '%u'\n", $u); // 无符号负整数表示
printf("%%f = '%f'\n", $n); // 浮点数表示
printf("%%o = '%o'\n", $n); // 八进制表示
printf("%%s = '%s'\n", $n); // 字符串表示
printf("%%x = '%x'\n", $n); // 十六进制表示（小写）
printf("%%X = '%X'\n", $n); // 十六进制表示（大写）
printf("%%+d = '%+d'\n", $n); // 正整数上的符号说明符
printf("%%+d = '%+d'\n", $u); // 负整数上的符号说明符
?>以上示例会输出：
%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'
示例 #2 printf()：字符串说明符
<?php
$s = 'monkey';
$t = 'many monkeys';
printf("[%s]\n", $s); // 标准字符串输出
printf("[%10s]\n", $s); // 带空格的右对齐
printf("[%-10s]\n", $s); // 带空格的左对齐
printf("[%010s]\n", $s); // 零填充也适用于字符串
printf("[%'#10s]\n", $s); // 使用自定义填充字符“#”
printf("[%'#*s]\n", 10, $s); // 提供填充的宽度作为附加参数
printf("[%10.9s]\n", $t); // 右对齐，但截断 8 个字符
printf("[%-10.9s]\n", $t); // 左对齐，但截断 8 个字符
?>以上示例会输出：
[monkey] [ monkey] [monkey ] [0000monkey] [####monkey] [####monkey] [ many monk] [many monk ]
参见
- print - 输出字符串
- sprintf() - 返回格式化字符串
- fprintf() - 将格式化后的字符串写入到流
- vprintf() - 输出格式化字符串
- vsprintf() - 返回格式化字符串
- vfprintf() - 将格式化字符串写入流
- sscanf() - 根据指定格式解析输入的字符
- fscanf() - 从文件中格式化输入
- number_format() - 以千位分隔符方式格式化一个数字
- date() - 格式化 Unix 时间戳
- flush() - 冲刷系统输出缓冲区
add a note
User Contributed Notes 17 notes
dhosek at excite dot com ¶
25 years ago
php at mole dot gnubb dot net ¶
19 years ago
[Editor's Note: Or just use vprintf...]
If you want to do something like <?php printf('There is a difference between %s and %s', array('good', 'evil')); ?> (this doesn't work) instead of <?php printf('There is a difference between %s and %s', 'good', 'evil'); ?> you can use this function:
<?php
function printf_array($format, $arr)
{
return call_user_func_array('printf', array_merge((array)$format, $arr));
}
?>
Use it the following way:
<?php
$goodevil = array('good', 'evil');
printf_array('There is a difference between %s and %s', $goodevil);
?>
and it will print:
There is a difference between good and evil
deekayen at hotmail dot com ¶
23 years ago
You can use this function to format the decimal places in a number:
$num = 2.12;
printf("%.1f",$num);
prints:
2.1
see also: number_format()
Mario M. Junior ¶
2 years ago
To provide a more user-friendly interface, you can use colors when printing text in the terminal.
p('Ordinary text.');
p('Warning: Check this out...', 'info');
p('Ops! Something went wrong.', 'error');
p('Yeah... done!', 'success');
function p($text, $style = '', $newLine = true) {
$styles = array(
'success' => "\033[0;32m%s\033[0m",
'error' => "\033[31;31m%s\033[0m",
'info' => "\033[33;33m%s\033[0m",
'Black' => "\033[0;30m%s\033[0m",
'Red' => "\033[0;31m%s\033[0m",
'Green' => "\033[0;32m%s\033[0m",
'Yellow' => "\033[0;33m%s\033[0m",
'Blue' => "\033[0;34m%s\033[0m",
'Purple' => "\033[0;35m%s\033[0m",
'Cyan' => "\033[0;36m%s\033[0m",
'Gray' => "\033[0;37m%s\033[0m",
'Graphite' => "\033[1;30m%s\033[0m",
'Bold Red' => "\033[1;31m%s\033[0m",
'Bold Green' => "\033[1;32m%s\033[0m",
'Bold Yellow' => "\033[1;33m%s\033[0m",
'Bold Blue' => "\033[1;34m%s\033[0m",
'Bold Purple' => "\033[1;35m%s\033[0m",
'Bold Cyan' => "\033[1;36m%s\033[0m",
'Bold White' => "\033[1;37m%s\033[0m",
'Bg Black' => "\033[40;1;37m%s\033[0m",
'Bg Red' => "\033[41;1;37m%s\033[0m",
'Bg Green' => "\033[42;1;37m%s\033[0m",
'Bg Yellow' => "\033[43;1;37m%s\033[0m",
'Bg Blue' => "\033[44;1;37m%s\033[0m",
'Bg Purple' => "\033[45;1;37m%s\033[0m",
'Bg Cyan' => "\033[46;1;37m%s\033[0m",
'Bg Gray' => "\033[47;1;37m%s\033[0m",
'Underscore' => "\033[4;37m%s\033[0m",
'Inverted' => "\033[7;37m%s\033[0m",
'Blink' => "\033[5;37m%s\033[0m",
);
$format = '%s';
if (isset($styles[$style])) {
$format = $styles[$style];
}
if ($newLine) {
$format .= PHP_EOL;
}
printf($format, $text);
}
maybird99 at yahoo dot com ¶
22 years ago
instead of writing a function to round off a float (let's call it 'x') accurately, it's much easier to add a small number to x and then truncate it...
For example: if you want to round off to the nearest integer, just add 0.5 to x and then truncate it. if x=12.6, then it would calculate 13.1, and truncate it to 13. If x=14.4, it would calculate 14.9 and truncate it to 14.
spiffytech at gmail dot com ¶
12 years ago
Be careful when relying on typecasting with printf(). For example,
printf("%d", "17,999")
returns "17".
shepard at ameth dot org ¶
23 years ago
Be sure that the output channel is available to write on before executing printf()! Some functions in classes available from various sources (in my case, DB_Sql::query() in PHPLIB) assume that printing will work, even after the default output stream has been closed.
For me the issue was most notable in PHP4 session management when I was creating my own sess_write() handler. Since I was unable to find any function that checks for the output stream that printf() uses, I just had to drop the crazy use of the printf(). (does some function already exist to check for the presence of an output stream?)
steve at myschoolsystems dot com ¶
3 years ago
To format a dollar value as in $123.00 that may otherwise look like $123 use this
print ('$'); // the dollar sign in front of our answer
printf ('%.2f',$price);
eugenew at starhub dot net dot sg ¶
22 years ago
If anyone is looking for writing a quine using printf(),
this is my example:
<?php $f='<?php $f=%c%s%c; printf($f,39,$f,39); ?>'; printf($f,39,$f,39); ?>
This also helps those who are new to printf() see one way of using the 'mixed args' part, rather than just a single argument as in most examples I've seen.
ezislis at mail dot ru ¶
22 years ago
be careful with integers, they cant hold large values.
printf("%d",10023123553.45634663);
will print out: 1433188961
and
printf("%.0f",10023123553.45634663);
will print out: 10023123553
RS ¶
8 years ago
If your missing features such as "-"*100 to print a single character multiple times you can use the slightly longer and less readable PHP equivalent printf("%'-100s",""); and sprint("%'-100s","").
dalu at uni SPAMHAM dot de ¶
22 years ago
copypasted from msdn
A format specification, which consists of optional and required fields, has the following form:
%[flags] [width] [.precision] [{h | l | I64 | L}]type
Each field of the format specification is a single character or a number signifying a particular format option. The simplest format specification contains only the percent sign and a type character (for example, %s). If a percent sign is followed by a character that has no meaning as a format field, the character is copied to stdout. For example, to print a percent-sign character, use %%.
The optional fields, which appear before the type character, control other aspects of the formatting, as follows:
type
Required character that determines whether the associated argument is interpreted as a character, a string, or a number (see the printf Type Field Characters table.
flags
Optional character or characters that control justification of output and printing of signs, blanks, decimal points, and octal and hexadecimal prefixes (see the Flag Characters table). More than one flag can appear in a format specification.
width
Optional number that specifies the minimum number of characters output (see printf Width Specification).
precision
Optional number that specifies the maximum number of characters printed for all or part of the output field, or the minimum number of digits printed for integer values (see the How Precision Values Affect Type table).
h | l | I64 | L
Optional prefixes to type-that specify the size of argument (see the Size Prefixes for printf and wprintf Format-Type Specifiers table).
creating dot www at gmail dot com ¶
9 years ago
Why rounding is not same as for round()?
Try this code:
<?php
printf("%.02lf\n", 1.035);
printf("%.02lf\n", round(1.035, 2));
?>
Result:
1.03
1.04
In my opion it should be:
1.04
1.04
Why is that?
sam[NOSPAM] at [NOSPAM]kingdomfaith dot com ¶
22 years ago
I don't know if this is useful to anyone, but here goes! Example for using the printf function to output an object.
class person
{
var $name = "";
function name($newname = NULL)
{
if(! is_null($newname))
{
$this->name=$newname;
}
return $this->name;
}
var $surname = "";
function surname($newsurname = NULL)
{
if(! is_null($newsurname))
{
$this->surname=$newsurname;
}
return $this->surname;
}
var $age = "";
function age($newage = NULL)
{
if(! is_null($newage))
{
$this->age=$newage;
}
return $this->age;
}
}
$bob = new person;
$bob->name('Bob');
$bob->surname('Builder');
$bob->age('50');
printf("Hi %s, your surname is %s and you are %s years old", $bob->name, $bob->surname, $bob->age);
Outputs:
Hi Bob, your surname is Builder and you are 50 years old
codeslinger at compsalot dot com ¶
19 years ago
Several people have commented about problems with aligning numbers. I just wanted to add a bit of clarification.
According to the spec all True Type Fonts (especially porpotional spaced fonts) use a fixed width for numeric digits. All digits have the same width which is equal to the width of "0".
Where things go haywire when trying to align numbers is that the space character does not have the same width as a digit when using a porportional spaced font.
Therefore if you want to line up a column of numbers, you can not use leading spaces to position them unless you use the same quantity of space characters for each row. e.g. your numbers have leading zeros etc.
The simplest solution is to switch to a monospaced font. Alternativly you can use positioning tags.
Summary: Your numbers will always line up properly regardless of the font used, if you get the starting position to be consistant.
kalai_msc29 at rediffmail dot com ¶
17 years ago
//If you want to make many Hidden fields you can use the function
//You can pass the values as array value,This will help you, when you are going to post many hiddend fields:-
function MakeHidden($ArrValues)
{
global $dearvar;
echo $dearvar;
if(is_array($ArrValues)){
foreach($ArrValues as $key=>$values)
{
echo $MakeHTML = "<input type='hidden' name='$values' value='$values'>";
}
}
else {
echo $MakeHTML = "<input type='hidden' name='$ArrValues' value='$ArrValues'>";
}
return $MakeHTML;
}
//example:-
MakeHidden(array("value1","value2","value3"));
//OutPut :-
<input type="hidden" value="value1" name="value1"/>
<input type="hidden" value="value2" name="value2"/>
<input type="hidden" value="value3" name="value3"/>
lordfarquaad at notredomaine dot net ¶
20 years ago
In response to chris dot breen at accurate dot com :
This will work, but i didn't try:
<?php
$format = 'The %2$s contains %1$d monkeys.
That is a nice %2$s full of %1$d monkeys.';
printf($format, $num, $location);
?>
Your problem came from the fact that in the string "\$s", the $ is simply escaped by the \, but but you must not do that with single quoted strings. Try to echo your strings to test it, or just go to http://www.php.net/manual/en/language.types.string.php
