Replaces the nth occurrence of a character in a string without a regular expression

For example there is a string: $a = ' Hello world hello pig hello cat Hello dog hello small boy '; Then I want to change the 3rd occurrence of Hello into good-bye, for example: ' Hello World Hello pig good-bye cat Hello dog hello small boy '; In this case, I will not find the PHP built-in function 1:30, and in the case of requirements can not use regular expressions, it is written this simple small function, if you have a good built-in function recommendation, welcome message:) Go from PHP interview question: http://phpmst.com/ !--? php /* * $text is the input text; * $word is the original string; * $cword is the string to be replaced; li> * $pos refers to the position of the nth occurrence of $word in $text, starting from 1, counting */ function Changenstr ($text, $word, $cword, $pos =1) { li> $text _array=explode ($word, $text); $num =count ($text _array)-1; if ($pos > $num) { return "The number is too big!or can not find the $word"; } $result _str= '; for ($i =0; $i <= $num; $i + +) { if ($i = = $pos-1) { $result _str.= $text _array[$i]. $cword; }else{ $result _str.= $text _array[$i]. $word; } return RTrim ($result _str, $word); } $text = ' Hello world hello pig hello cat Hello dog hello small boy '; $word = ' Hello '; $cword = ' good-bye '; Echo changenstr ($text, $word, $cword, 3); //output: Hello World Hello pig good-bye cat Hello dog Hello small boy ? Copy Code

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