php在指定字符串中查找子字符串

对strpos()函数可以用来在php中查找子字符串。strpos()函数将试图找到子字符串在源字符串中首次出现的位置。如果找到了，它会返回一个非负整数表示子字符串出现的位置。 否则它会返回一个布尔值false。

1. $haystack1 = "2349534134345w3mentor16504381640386488129";
2. $haystack2 = "w3mentor234953413434516504381640386488129";
3. $haystack3 = "center234953413434516504381640386488129fyi";
4. $pos1 = strpos($haystack1, "w3mentor");
5. $pos2 = strpos($haystack2, "w3mentor");
6. $pos3 = strpos($haystack3, "w3mentor");
7. print("pos1 = ($pos1); type is " . gettype($pos1) . "\n");
8. print("pos2 = ($pos2); type is " . gettype($pos2) . "\n");
9. print("pos3 = ($pos3); type is " . gettype($pos3) . "\n");
10. ?>

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输出结果

1. pos1 = (13); type is integer
2. pos2 = (0); type is integer
3. pos3 = (); type is boolean
5. pos3返回的是bool值，即没有找到子字符串

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