PHP writes the formatted string into a variable using sprintf()

Possible format values:

• %% - returns a percent sign %

• %b - a binary number

• %c - the character corresponding to the ASCII value

• %d - the decimal number containing the sign (negative, 0, positive)

• %e - Use lowercase scientific notation (e.g. 1.2e+2)

• ##%E - Use uppercase scientific notation (e.g. 1.2E+ 2)

• %u - Decimal number without sign (greater than or equal to 0)

• %f - Floating point number (local setting) )

• %F - floating point number (non-native setting)

##%g - shorter %e and %f
%G - shorter %E and %f

• ##%o - octal number

• %s - character String

• %x - Hexadecimal number (lowercase letters)

• ##%X - Hexadecimal number (uppercase letters)

• Additional format value. Must be placed between % and a letter (e.g. %.2f):

+ (Add + or - in front of a number to define the sign of the number. By default, only Negative numbers are marked, positive numbers are not marked)

• ' (Specifies what to use as padding, the default is spaces. It must be used with the width specifier. For example: %'x20s ( Use "x" as padding))

• - (Adjust the variable value left)

• [0-9] (Specify the minimum variable value Width)

• .[0-9] (Specifies the number of decimal places or the maximum string length)

• Note: If you use more than one of the above The format values ​​must be used in the order above and cannot be disrupted.

技术细节

更多实例

实例 1

使用格式值 %f：

<?php
$number = 123;
$txt = sprintf("%f",$number);
echo $txt;
?>

实例 2

使用占位符：

<?php
$number = 123;
$txt = sprintf("With 2 decimals: %1$.2f
<br>With no decimals: %1$u",$number);
echo $txt;
?>

实例 3

所有可能的格式值的演示：

<?php
$num1 = 123456789;
$num2 = -123456789;
$char = 50; // The ASCII Character 50 is 2

// Note: The format value "%%" returns a percent sign
echo sprintf("%%b = %b",$num1)."<br>"; // Binary number
echo sprintf("%%c = %c",$char)."<br>"; // The ASCII Character
echo sprintf("%%d = %d",$num1)."<br>"; // Signed decimal number
echo sprintf("%%d = %d",$num2)."<br>"; // Signed decimal number
echo sprintf("%%e = %e",$num1)."<br>"; // Scientific notation (lowercase)
echo sprintf("%%E = %E",$num1)."<br>"; // Scientific notation (uppercase)
echo sprintf("%%u = %u",$num1)."<br>"; // Unsigned decimal number (positive)
echo sprintf("%%u = %u",$num2)."<br>"; // Unsigned decimal number (negative)
echo sprintf("%%f = %f",$num1)."<br>"; // Floating-point number (local settings aware)
echo sprintf("%%F = %F",$num1)."<br>"; // Floating-point number (not local sett aware)
echo sprintf("%%g = %g",$num1)."<br>"; // Shorter of %e and %f
echo sprintf("%%G = %G",$num1)."<br>"; // Shorter of %E and %f
echo sprintf("%%o = %o",$num1)."<br>"; // Octal number
echo sprintf("%%s = %s",$num1)."<br>"; // String
echo sprintf("%%x = %x",$num1)."<br>"; // Hexadecimal number (lowercase)
echo sprintf("%%X = %X",$num1)."<br>"; // Hexadecimal number (uppercase)
echo sprintf("%%+d = %+d",$num1)."<br>"; // Sign specifier (positive)
echo sprintf("%%+d = %+d",$num2)."<br>"; // Sign specifier (negative)
?>

先举个最简单的案例

<?php
$str1="1234";

echo sprintf("hello%s","$str1");

//效果为： hello1234


?>

这什么意思呢

要点：

%s = %符号和后面属性符号(s)总称为插入标记组合，也就是把后面准备进行格式化的值($str1)替换在这个位置 

hello = 这个单词就是很多人蒙蔽的地方，告诉你这个什么代表也没有，就单纯的代表一个hello，用于分割或者修饰用，一般用[ %s ]、<%s>这样格式化出来后就直接在标签里

记住，一个%标记符后面只有一个类型属性（比如s），s是什么上面有，以字符串的方式格式化

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