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PHP 中的 fprintf() 函数
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Definition and Usage
定义和用法
The fprintf() function writes a formatted string to a specified output stream (example: file or database).
fprintf()函数的作用是：输出格式化字符串到流 / 将格式化后的字符串写到输出流。
The arg1, arg2, ++ parameters will be inserted at percent (%) signs in the main string. This function works "step-by-step". At the first % sign, arg1 is inserted, at the second % sign, arg2 is inserted, etc.
arg1, arg2, ++参数将被插入到主体字符串中的百分号（%）之后。这个函数是“一步一步[step-by-step]”执行的。在第一个“%”之后插入arg1，在第二个“%”之后插入arg2，依次类推。
The fprintf() function returns the length of the written string.
fprintf()函数将返回书写的字符串长度。
Syntax
语法
fprintf(stream,format,arg1,arg2,arg++) |
| Parameter参数 | Description描述 |
|---|---|
| stream | Required. Specifies where to write/output the string 必要参数。指定从哪个位置书写 / 输出字符串 |
| format | Required. Specifies the string and how to format the variables in it. 必要参数。指定字符串，以及如何定义其中变量的格式。 Possible format values:
Additional format values. These are placed between the % and the letter (example %.2f):
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 必要参数。这个自变量（arg1）必须安插在第一个%-符号前 |
| arg2 | Optional. The argument to be inserted at the second %-sign in the format string 可选参数。这个自变量（arg2）必须安插在第二个%-符号前 |
| arg++ | Optional. The argument to be inserted at the third, fourth, etc. %-sign in the format string 可选参数。与上述自变量相同，它们可以安插在第三个、第四个……（依次类推）%-符号前。 |
Tips and Notes
提示和注意点
Note: If there are more % signs than arguments, you must use placeholders. A placeholder is inserted after the % sign, and consists of the argument- number and "$". See example three.
注意：如果这里的%比自变量更多，你必须使用占位符[placeholders]。占位符是安插在%之后的，它是由自变量-数字和“$”组成的。具体可以见案例3。
Tip: Related functions: printf(), sprintf(), vfprintf(), vprintf(), and vsprintf().
提示：相关函数：printf(), sprintf(), vfprintf(), vprintf(), 和 vsprintf()
Example 1
案例1
<?php
$str = "Hello";
$number = 123;
$file = fopen("test.txt","w");
echo fprintf($file,"%s world. Day number %u",$str,$number);
?> |
The output of the code above will be:
上述代码将输出下面的结果：
27 |
The following text will be written to the file "test.txt":
下面的文本将被写入文件“text.txt”：
Hello world. Day number 123 |
Example 2
案例2
<?php
$number = 123;
$file = fopen("test.txt","w");
fprintf($file,"%f",$number);
?> |
The following text will be written to the file "test.txt":
下面的文本将被写入文件“text.txt”：
123.000000 |
Example 3
案例3
Use of placeholders:
使用占位符
<?php
$number = 123;
$file = fopen("test.txt","w");
fprintf($file,"With 2 decimals: %1$.2f
nWith no decimals: %1$u",$number);
?> |
The following text will be written to the file "test.txt":
下面的文本将被写入文件“text.txt”：
With 2 decimals: 123.00 With no decimals: 123 |
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