check if string starts with php

//php check if first four characters of a string = http
substr( $http, 0, 4 ) === "http";
//php check if first five characters of a string = https
substr( $https, 0, 5 ) === "https";

phpCopy<?php
  $string = "Mr. Peter";
  if(strncmp($string, "Mr.", 3) === 0){
      echo "The string starts with the desired substring.";
  }else 
      echo "The string does not start with the desired substring.";
?>

phpCopy<?php
  $string = "Mr. Peter";
  if(substr($string, 0, 3) === "Mr."){
      echo "The string starts with the desired substring.";
  }else 
      echo "The string does not start with the desired substring.";
?>

substr( $string_n, 0, 4 ) === "http"

phpCopy<?php
  $string = "Mr. Peter";
  if(strpos( $string, "Mr." ) === 0){
      echo "The string starts with the desired substring.";
  }else 
      echo "The string does not start with the desired substring.";
?>

phpCopy<?php
  $string = "mr. Peter";
  if(strncasecmp($string, "Mr.", 3) === 0){
      echo "The string starts with the desired substring.";
  }else 
      echo "The string does not start with the desired substring.";
?>