Find character in string

Question

How to find the position of a given character, where the string has many of these characters in the same string, for example: find the 3rd letter X in the string Y. some way to accomplish this?

Answer 1

usa strpos http://php.net/manual/en/function.strpos.php

where you can make a loop by passing the $offset from where the function should start to search

---

Something like that

<?php

$texto = "um texto muito longo cheio de letras, numeros, fatos, historias, aventuras e altas confusões na sessao da tarde.";
$achar = "a";
$posicoes = array();
$offset = 0;

while ( ($pos = strpos($texto, $achar, $offset)) !== false) {

    $posicoes[] = $pos;
    $offset = $pos+1;
}

print_r($posicoes);

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Update

if you want you can also use regular expressions, which in my opinion is much more elegant:

<?php

$re = "/a/";
$str = "um texto muito longo cheio de letras, numeros, fatos, historias, aventuras e altas confusões na sessao da tarde.";

preg_match_all($re, $str, $resultados, PREG_OFFSET_CAPTURE);

print_r($resultados);

Answer 2

This calls for a specialized function. Well, I quickly developed the following:

function nthstrpos($haystack, $needle, $nth) {
    $count = 0;
    $pos = -1;
    do {
        $pos = strpos($haystack, $needle, $pos + 1);
        $count++;
    } while ($pos !== false && $count < $nth);
    return $pos;
}

The function nthstrpos() receives three parameters:

1. Text to be searched (haystack)
2. Text to be searched for (needle)
3. Number of occurrence to be located (nth occurrence of the previous parameter), where 1 the first occurrence and so on

For example, the command nthstrpos('banana', 'a', 2) will return the second occurrence of the letter a in the text banana.

If the text to be searched is not found or the number of the requested occurrence exceeds the total of existing occurrences the return will be false.

Run in Ideone

Answer 3

Use the function strpos. Its parameters are:

• $haystack: To string in which the search will be made.
• $needle: Characters to be searched.
• $offset: This parameter allows you to define from which character in $haystack start the search.

We can use this last parameter to do this type of search, like this:

function strposNth($texto, $procurar, $n){
    switch($n){
        case $n === 0:
            return false;
            break;
        case $n === 1:
            return(strpos($texto, $encontrar) + 1);
            break;
        default:
            return(strpos($texto, $procurar, strposNth($texto, $procurar, $n - 1) +
            strlen($procurar)) + 1);
            break;
    }
}

To use it:

echo strposNth("overflow", "o", 2); // 7

DEMO

Answer 4

$test = "Hi, How are you!";

function strCharFind($needle,$haystack){
    $return = FALSE;
    $arr = str_split($haystack,1);
    foreach($arr as $value){
        if($value==strtolower($needle)||$value==strtoupper($needle)){
            $return = TRUE;
        }
    }
    return $return;
}

var_dump(strCharFind(',',$test));//true
var_dump(strCharFind('h',$test));//true
var_dump(strCharFind('!',$test));//true
var_dump(strCharFind('?',$test));//false