php地图数字到字符串

Question

I am trying to write a program in php which first prompts a user for a string. once they enter a string it is supposed to give the equivalent digits if it were on a phone. eg ABC(2) , DEF(3) , GHI(4) , JKL(5) , MNO(6) , PQRS(7) , TUV(8) , WXYZ(9). Im using a for loop and nested if statements but i am not getting the correct output. Am I going about this the right way? my code is below

<?php

$str = $_POST['usersString'];

$len = strlen($str);

for($i=0; $i<$len-1; $i++){
    if($i="a" || $i="b" || $i="c"){
        echo "1";
    }

    if($i="d" || $i="e" || $i="f"){
        echo "2";
    }

    if($i="g" || $i="h" || $i="i"){
        echo "3";
    }
}    

?>
<form action="task17.php" method="POST">
Enter a string <input type="text" name="usersString" />
<input type="submit" value="enter" />
</form> 

Answer 1

<?php

$str = $_POST['usersString'];

$len = strlen($str);

for($i=0; $i<$len; $i++){

   if($str[$i]=="a" || $str[$i]=="b" || $str[$i]=="c"){
    echo "1";

   }else if($str[$i]=="d" || $str[$i]=="e" || $str[$i]=="f"){
    echo "2";

   }else if($str[$i]=="g" || $str[$i]=="h" || $str[$i]=="i"){
    echo "3";
   }
}    

?>

your condition is wrong $i="a" It should be $str[$i]=="a"