PHP使用str_replace将数字更改为字符串而不混淆

Question

I am changing numbers to the strings. Like that:

1=>A
2=>B
3=>C
4=>D
5=>E
6=>F
7=>G
8=>H
9=>I
10=>J
11=>K
12=>L

I made this function to be replace:

function name($string) {
    $find=array("1","2","3","4","5","6","7","8","9","10","11","12");
    $replace=array("A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L");
    $string=str_replace($find,$replace,$string);  
    return $string;
}

But if i use this: name("12"); its not returning L its return AB .

Actually its make sense. Returning each letter. How can i return L in this function? What should i do? Thanks in advance.

Answer 1

The str_replace() with array replace provided string with any match in array items. So use array_search() like shown in bottom instead

$result = $replace[array_search($string, $find)]; 

So your code changed to

function name($string) {
    $find = array("1","2","3","4","5","6","7","8","9","10","11","12");
    $replace = array("A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L");  
    return $replace[array_search($string, $find)]; 
}

Check result in demo

Answer 2

The problem is that str_replace() just replaces them in the order that you specify as stated in the documentation ...

Replacement order gotcha

Because str_replace() replaces left to right, it might replace a previously inserted value when doing multiple replacements. See also the examples in this document.

If you instead use strtr() it will replace them longest first...

$string=strtr($string, array_combine($find, $replace));

Answer 3

You do have a PHP function for what you are trying to achieve - chr

<?php 

function name($string) {
   return chr(intval($string) + 64);
}

UPDATE:

• Thanks to @Ulrich. You can better describe the above solution using ord('A') . So, basically you add the ASCII value of A to the integer converted string parameter and subtract 1 from it, to get the ASCII value for the character we are seeking. chr() finally gives us that character.

function name($string) {
   return chr(intval($string) + ord('A') - 1);
}

Answer 4

Create a simple mapping:

$mapping = [
    '1' => 'A',
    '2' => 'B',
    '12' => 'L',
];
if (!array_key_exists($string, $mapping)) {
    throw new Exception('invalid input provided');
}
return $mapping[$string];

Answer 5

If I don't understood your question then , Try with range() instead of long key=>value array. I think for your current requirement str_repalce() is not a good choice, simple range() will do the magic :)

<?php
  function name($num){
    $array = range('A','Z');
    $array = array_filter(array_merge(array(0), $array));
    return $array[$num];
  }

 echo name(12);

DEMO: https://3v4l.org/kl9jn

Answer 6

instead of str_replace use chr

function name($string) {
    return chr( $string + 64 );
}

note that this will word as long a $string is actually containing a number in the range 1 .. 26

---

But if -for some reason- you want to stick with the str_replace approach a solution is to pad numbers with a leading and following space (or a character of your choice...), this way:

function name($string) {
    $string = " " . $string . " ";
    $find=array(" 1 "," 2 "," 3 "," 4 "," 5 "," 6 "," 7 "," 8 "," 9 "," 10 "," 11 "," 12 ");
    $replace=array("A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L");
    $string=str_replace($find,$replace,$string);  
    return $string;
}