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PHP 中的 vfprintf() 函数
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Definition and Usage
定义和用法
The vfprintf() function writes a formatted string to a specified output stream (example: file or database).
vfprintf()函数的作用是：输出格式化字符串到流（例如：文件或数据库）。
Unlike fprintf(), the arguments in vfprintf(), are placed in an array. The array elements will be inserted at the percent (%) signs in the main string. This function works "step-by-step". At the first % sign, the first array element is inserted, at the second % sign, the second array element is inserted, etc.
与fprintf()函数不同，vfprintf()函数中的自变量是位于数组中的，数组元素的字符串之前都要加上百分号（%）。这个函数是“一步一步[step-by-step]”按顺序执行。在第一个%后，将插入第一个数组元素；在第二个%后，将插入第二个数组元素，依次类推。
The vfprintf() function returns the length of the written string.
vfprintf()函数将返回写入的字符串长度。
Syntax
语法
vfprintf(stream,format,argarray) |
| 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. |
| argarray | Required. An array with arguments to be inserted at the % signs in the format string 必要参数。指定在格式化字符串中插在%之后的带有自变量的数组对象 |
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 "$". See example three.
注意：注意：如果这里的%比自变量更多，你必须使用占位符[placeholders]。占位符是安插在%之后的，它是由自变量-数字和“$”组成的。具体可以见案例3。
Tip: Related functions: fprintf(), printf(), sprintf(), 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;
$file = fopen("test.txt","w");
echo vfprintf($file,"%s world. Day number %u",array($str,$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
$num1 = 123;
$num2 = 456;
$file = fopen("test.txt","w");
vfprintf($file,"%f%f",array($num1,$num2));
?> |
The following text will be written to the file "test.txt":
下面的文本将被写入文件“text.txt”：
123.000000456.000000 |
Example 3
案例3
Use of placeholders:
使用占位符
<?php
$number = 123;
$file = fopen("test.txt","w");
vfprintf($file,"With 2 decimals: %1$.2f
nWith no decimals: %1$u",array($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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