php 如何使用 strpos 确定输入字符串中是否存在字符串？
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How to use strpos to determine if a string exists in input string?
提问by Scott B
$filename = 'my_upgrade(1).zip';
$match = 'my_upgrade';
if(!strpos($filename, $match))
{
die();
}
else
{
//proceed
}
In the code above, I'm trying to die out of the script when the filename does not contain the text string "my_upgrade". However, in the example given, it should not die since "my_upgrade(1).zip" contains the string "my_upgrade".
在上面的代码中，当文件名不包含文本字符串“my_upgrade”时，我试图退出脚本。但是，在给出的示例中，它不应该死，因为“ my_upgrade(1).zip”包含字符串“ my_upgrade”。
What am I missing?
我错过了什么？
回答by phihag
strposreturns falseif the string is not found, and 0if it is found at the beginning. Use the identity operatorto distinguish the two:
strposfalse如果未找到字符串，并且0在开头找到它，则返回。使用身份运算符区分两者：
if (strpos($filename, $match) === false) {
By the way, this fact is documented with a red background and an exclamation mark in the official documentation.
顺便说一下，官方文档中以红色背景和感叹号记录了这一事实。
回答by Rishabh
The strpos()function is case-sensitive.
该strpos()函数区分大小写。
if(strpos($filename, $match) !== false)
{
// $match is present in $filename
}
else
{
// $match is not present in $filename
}
For using case-insensitive.use stripos()that is it finds the position of the first occurrence of a string inside another string (case-insensitive)
用于不区分大小写。用途stripos()是它在另一个字符串中找到一个字符串第一次出现的位置（不区分大小写）
回答by Maxime Fafard
if (strpos($filename, $match) === false)
Otherwise, strposwill return 0(the index of the match), which is false.
否则，strpos将返回0（匹配的索引），即false。
The ===operator will also compare type of the variables (boolean != integer)
该===运营商也将比较变量的类型（布尔！=整数）
回答by hakre
false === strpos($filename, $match)
The strposfunctionDocsreturns falseif not found or 0if found on position 0(programmers like to start counting at 0often):
该strpos函数的文档返回false，如果没有找到或者0如果在位置上被发现0（程序员喜欢在开始计数0常）：
WarningThis function may return Boolean
FALSE, but may also return a non-Boolean value which evaluates toFALSE, such as0or"". Please read the section on Booleans for more information. Use the===operator for testing the return value of this function.
警告此函数可能返回 Boolean
FALSE，但也可能返回计算结果为 的非布尔值FALSE，例如0或""。请阅读有关布尔值的部分以获取更多信息。使用===运算符来测试这个函数的返回值。
回答by Atanas Atanasov
This working for me when everything other fail in some situations:
当其他一切在某些情况下失败时，这对我有用：
$filename = 'my_upgrade(1).zip';
$match = 'my_upgrade';
$checker == false;
if(strpos($filename, $match))
{
$checker == true;
}
if ($checker === false)
{
die();
}
else
{
//proceed
}
Or in short:
或者简而言之：
$filename = 'my_upgrade(1).zip';
$match = 'my_upgrade';
$checker == false;
if(strpos($filename, $match))
{
$checker == true;
//proceed
}
if ($checker === false)
{
die();
}
回答by Abhishek Gupta
$data = 'match';
$line = 'match word in this line';
if(strpos($line,$data) !== false){
echo "data found";
}else{
echo "no data found";
}回答by John Percival Hackworth
strpos in this case will return a zero, which is then interpretted as false when you do the logical negation. You should check explicitly for the boolean false.
在这种情况下 strpos 将返回一个零，然后在您进行逻辑否定时将其解释为 false。您应该明确检查 boolean false。
