Reply_Message telegram bot api - telegram-bot

Question

i cannot understand the Reply_to_message method for telegram bot api. here is my code :
<?php
define('API_KEY','My_token');
function bot($method,$datas=[]){
$url = "https://api.telegram.org/bot".API_KEY."/".$method;
$ch = curl_init();
curl_setopt($ch,CURLOPT_URL,$url);
curl_setopt($ch,CURLOPT_RETURNTRANSFER,true);
curl_setopt($ch,CURLOPT_POSTFIELDS,http_build_query($datas));
$res = curl_exec($ch);
if(curl_error($ch)){
var_dump(curl_error($ch));
}else{
return json_decode($res);
}
}
$update = json_decode(file_get_contents('php://input'));
if($update->message->text == '/start'){
bot('sendMessage',[
'chat_id'=>$update->message->chat->id,
'text'=>'Hello word!'
]);
}
here when user send /start the bot send hello world text. i wanna user reply to message for sending hello world. i mean when user send /start the bot reply's to message with the text 'Hello world!'
im using webhook.

Answer 1

You need to add the key reply_to_message_id to the object you are posting and set the id of the message you want to reply to as the value.
if($update->message->text == '/start'){
bot('sendMessage',[
'chat_id'=>$update->message->chat->id,
'text'=>'Hello word!',
'reply_to_message_id' => $update->message->message_id
]);
}