PHP fprintf() 函数

示例

将一些文本写入名为 "test.txt" 的文本文件：

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

上面代码的输出将是：

以下文本将写入文件"test.txt"：

There are 9 million bicycles in Beijing.

定义和用法

fprintf() 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）。

arg1、arg2、++ 参数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 arg1，在第二个 % 符号处插入 arg2，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：打印（）,sprintf(),vprintf(),vsprintf()和vfprintf()

语法

fprintf( stream,format,arg1,arg2,arg++)

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.
arg1	Required. The argument to be inserted at the first %-sign in the format string
arg2	Optional. The argument to be inserted at the second %-sign in the format string
arg++	Optional. The argument to be inserted at the third, fourth, etc. %-sign 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
$number = 123;
$file = fopen("test.txt","w");
fprintf($file,"%f",$number);
?>

以下文本将写入文件"test.txt"：

123.000000

示例

占位符的使用：

<?php
$number = 123;
$file = fopen("test.txt","w");
fprintf($file,"With 2 decimals: %1\$.2f
\nWith no decimals: %1\$u",$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 ",$num1); // Binary number
printf("%%c = %c ",$char); // The ASCII Character
printf("%%d = %d ",$num1); // Signed decimal number
printf("%%d = %d ",$num2); // Signed decimal number
printf("%%e = %e ",$num1); // Scientific notation (lowercase)
printf("%%E = %E ",$num1); // Scientific notation (uppercase)
printf("%%u = %u ",$num1); // Unsigned decimal number (positive)
printf("%%u = %u ",$num2); // Unsigned decimal number (negative)
printf("%%f = %f ",$num1); // Floating-point number (local settings aware)
printf("%%F = %F ",$num1); // Floating-point number (not local settings aware)
printf("%%g = %g ",$num1); // Shorter of %e and %f
printf("%%G = %G ",$num1); // Shorter of %E and %f
printf("%%o = %o ",$num1); // Octal number
printf("%%s = %s ",$num1); // String
printf("%%x = %x ",$num1); // Hexadecimal number (lowercase)
printf("%%X = %X ",$num1); // Hexadecimal number (uppercase)
printf("%%+d = %+d ",$num1); // Sign specifier (positive)
printf("%%+d = %+d ",$num2); // Sign specifier (negative)
?>

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