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HomeBackend DevelopmentPHP TutorialPHP中读写文件实现代码_php技巧

在PHP中读写文件,可以用到一下内置函数:

1.fopen(创建文件和打开文件)
语法:

复制代码 代码如下:
fopen(filename,mode)

filename,规定要打开的文件。mode,打开文件的模式,可能的值见下表。

mode 说明

"r" 只读方式打开,将文件指针指向文件开头。
"r+" 读写方式打开,将文件指针指向文件开头。
"w" 写入方式打开,将文件指针指向文件开头并将文件大小截为零。如果文件不存在则尝试创建。
"w+" 读写方式打开,将文件指针指向文件开头并将文件大小截为零。如果文件不存在则尝试创建。
"a" 写入方式打开,将文件指针指向文件末尾。如果文件不存在则尝试创建。
"a+" 读写方式打开,将文件指针指向文件末尾。如果文件不存在则尝试创建。
如果成功打开文件,fopen函数的返回值是一个文件指针,如果出错,返回 FALSE。

示例:
复制代码 代码如下:

$fp = fopen("test.txt", "r");
?>

2.fclose(关闭文件)
语法:

fclose(filepointer)
filepointer,要关闭的文件指针。如果成功,fclose 函数返回 TRUE,如果失败,fclose 函数返回 FALSE。
示例:
复制代码 代码如下:

$fp = fopen("test.txt", "r");
fclose($fp);
?>

3.feof(检测是否已到达文件末尾)
语法:

feof(filepointer)
filepointer,要检测的文件指针,该指针必须指向成功打开没有关闭的文件。如果文件指针到了文件末尾或者出错时,feof函数返回 TRUE。
示例:
复制代码 代码如下:

$fp = fopen("test.txt", "r");
while(! feof($fp))
{
echo fgets($fp). "
";
}
fclose($fp);
?>

4.fgets(从文件指针中读取一行)
语法:

fgets(filepointer)
filepointer,要读取的文件指针。如果成功,从文件中读取一行并返回字符串,如果失败,返回 FALSE。
示例:
复制代码 代码如下:

$fp = fopen("test.txt", "r");
if($fp)
{
for($i=1;! feof($fp);$i++)
{
echo "行".$i." : ".fgets($fp). "
";
}
}
else
{
echo "打开文件失败";
}
fclose($fp);
?>

假设test.txt的内容为:

hello world
hello cnblogs
hello heihaozi
hello everyone
页面输出的结果为:

行1 : hello world
行2 : hello cnblogs
行3 : hello heihaozi
行4 : hello everyone
5.fwrite(写入文件)
语法:

fwrite(filepointer,string)
filepointer,要写入的文件指针。string,要写入的字符串。如果成功,返回写入的字符数,如果失败,返回 FALSE。
示例:
复制代码 代码如下:

$fp = fopen("test.txt", "w");//文件被清空后再写入
if($fp)
{
$count=0;
for($i=1;$i{
$flag=fwrite($fp,"行".$i." : "."Hello World!\r\n");
if(!$flag)
{
echo "写入文件失败
";
break;
}
$count+=$flag;
}
echo "共写入".$count."个字符";
}
else
{
echo "打开文件失败";
}
fclose($fp);
?>

页面输出的结果为:

共写入100个字符
test.txt文件会被写入:

行1 : Hello World!
行2 : Hello World!
行3 : Hello World!
行4 : Hello World!
行5 : Hello World!
  
注:为了简化操作,部分函数的可选参数没有列出。
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