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目录

PHP vfprintf() 函数

❮ PHP 字符串参考

示例

将一些文本写入名为 "test.txt" 的文本文件：

<?php
$number = 9;
$str = "Beijing";
$file = fopen("test.txt","w");
echo vfprintf($file,"There are %u million bicycles in %s.",array($number,$str));
?>

上面代码的输出将是：

40

以下文本将写入文件"test.txt"：

There are 9 million bicycles in Beijing.

定义和用法

vfprintf() 函数将格式化字符串写入指定的输出流（例如：文件或数据库）。

与 fprintf() 不同，vfprintf() 中的参数放置在一个数组中。数组元素将插入到主字符串中的百分号 (%) 处。此功能有效"step-by-step"。在第一个 % 符号处，插入第一个数组元素，在第二个 % 符号处，插入第二个数组元素，依此类推。

笔记：如果 % 符号多于参数，则必须使用占位符。占位符插入到 % 符号之后，由参数数字和 "\$" 组成。参见示例二。

提示：相关功能：fprintf(),打印（）,sprintf(),vprintf()和vsprintf()。

语法

vfprintf( stream,format,argarray)

参数值

Parameter Description
stream Required. Specifies where to write/output the string
format Required. Specifies the string and how to format the variables in it.

Possible format values:

  • %% - Returns a percent sign
  • %b - Binary number
  • %c - The character according to the ASCII value
  • %d - Signed decimal number (negative, zero or positive)
  • %e - Scientific notation using a lowercase (e.g. 1.2e+2)
  • %E - Scientific notation using a uppercase (e.g. 1.2E+2)
  • %u - Unsigned decimal number (equal to or greather than zero)
  • %f - Floating-point number (local settings aware)
  • %F - Floating-point number (not local settings aware)
  • %g - shorter of %e and %f
  • %G - shorter of %E and %f
  • %o - Octal number
  • %s - String
  • %x - Hexadecimal number (lowercase letters)
  • %X - Hexadecimal number (uppercase letters)

Additional format values. These are placed between the % and the letter (example %.2f):

  • + (Forces both + and - in front of numbers. By default, only negative numbers are marked)
  • ' (Specifies what to use as padding. Default is space. Must be used together with the width specifier. Example: %'x20s (this uses "x" as padding)
  • - (Left-justifies the variable value)
  • [0-9] (Specifies the minimum width held of to the variable value)
  • .[0-9] (Specifies the number of decimal digits or maximum string length)

Note: If multiple additional format values are used, they must be in the same order as above.
argarray Required. An array with arguments to be inserted at the % signs in the format string

技术细节

返回值： 返回写入字符串的长度
PHP 版本： 5+

更多示例

示例

将一些文本写入文件：

<?php
$num1 = 123;
$num2 = 456;
$file = fopen("test.txt","w");
vfprintf($file,"%f%f",array($num1,$num2));
?>

以下文本将写入文件"test.txt"：

123.000000456.000000

示例

占位符的使用：

<?php
$number = 123;
$file = fopen("test.txt","w");
vfprintf($file,"With 2 decimals: %1\$.2f
\nWith no decimals: %1\$u",array($number));
?>

以下文本将写入文件"test.txt"：

With 2 decimals: 123.00
With no decimals: 123

示例

使用 printf() 演示所有可能的格式值：

<?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)
?>
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❮ PHP 字符串参考