PHP outputs formatted string function printf()

Example

Output a formatted string:

<?php
$number = 9;
$str = "Beijing";
printf("There are %u million bicycles in %s.",$number,$str);
?>

Definition and usage

The printf() function outputs a formatted string.

arg1, arg2, ++ parameters will be inserted into the main string at the percent sign (%) symbol. This function is executed step by step. At the first % sign, insert arg1, at the second % sign, arg2, and so on.

Note: If there are more % symbols than arg arguments, you must use placeholders. The placeholder is inserted after the % symbol and consists of a number and "\$". See Example 2.

Tip: Related functions: sprintf(), vprintf(), vsprintf(), fprintf() and vfprintf()

Syntax

printf(format,arg1,arg2,arg++)

Required. Specifies the parameters to be inserted at the first % sign in the format string. Optional. Specifies the parameter to be inserted into the format string at the second % sign. Optional. Specifies the parameters to be inserted into the format string at the third, fourth, etc. % symbols.

Parameters	Description
format	Required. Specifies a string and how to format variables within it. 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. arg1
	arg2
	arg++
	技术细节 返回值：             返回被输出字符串的长度。     PHP 版本：         4+     更多实例 实例 1 使用格式值 %f： <?php $number = 123; printf("%f",$number); ?> 实例 2 使用占位符： <?php $number = 123; printf("With 2 decimals: %1$.2f <br>With no decimals: %1$u",$number); ?> 实例 3 所有可能的格式值的演示： <?php $num1 = 123456789; $num2 = -123456789; $char = 50; // The ASCII Character 50 is 2 // Note: The format value "%%" returns a percent sign printf("%%b = %b <br>",$num1); // Binary number printf("%%c = %c <br>",$char); // The ASCII Character printf("%%d = %d <br>",$num1); // Signed decimal number printf("%%d = %d <br>",$num2); // Signed decimal number printf("%%e = %e <br>",$num1); // Scientific notation (lowercase) printf("%%E = %E <br>",$num1); // Scientific notation (uppercase) printf("%%u = %u <br>",$num1); // Unsigned decimal number (positive) printf("%%u = %u <br>",$num2); // Unsigned decimal number (negative) printf("%%f = %f <br>",$num1); // Floating-point number (local settings aware) printf("%%F = %F <br>",$num1); // Floating-point number (not local settings aware) printf("%%g = %g <br>",$num1); // Shorter of %e and %f printf("%%G = %G <br>",$num1); // Shorter of %E and %f printf("%%o = %o <br>",$num1); // Octal number printf("%%s = %s <br>",$num1); // String printf("%%x = %x <br>",$num1); // Hexadecimal number (lowercase) printf("%%X = %X <br>",$num1); // Hexadecimal number (uppercase) printf("%%+d = %+d <br>",$num1); // Sign specifier (positive) printf("%%+d = %+d <br>",$num2); // Sign specifier (negative) ?> 实例 4 字符串说明符的演示： <?php $str1 = "Hello"; $str2 = "Hello world!"; printf("[%s]<br>",$str1); printf("[%8s]<br>",$str1); printf("[%-8s]<br>",$str1); printf("[%08s]<br>",$str1); printf("[%&#39;*8s]<br>",$str1); printf("[%8.8s]<br>",$str2); ?> printf()函数优点在于可以格式化输出! printf的格式控制的完整格式： % - 0 m.n l或h 格式字符 下面对组成格式说明的各项加以说明： ①%：表示格式说明的起始符号，不可缺少。 ②-：有-表示左对齐输出，如省略表示右对齐输出。 ③0：有0表示指定空位填0,如省略表示指定空位不填。 ④m.n：m指域宽，即对应的输出项在输出设备上所占的字符数。N指精度。用于说明输出的实型数的小数位数。为指定n时，隐含的精度为n=6位。 ⑤l或h:l对整型指long型，对实型指double型。h用于将整型的格式字符修正为short型。

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