Optimization of php code (NF key generation)

Question

Dear colleagues, currently I am working on a project that carries out the sending of tax coupons, in it I arrived at a function that generates the key of the nfe, in it I receive the following data:

• City code
• Year and Month of issue
• Cnpj of the Company
• Model of the note (65 in the case)
• Series
• Note number (9 positions)
• Type of issue
• Note number with 8 positions

Function code:

public function GeraChaveNFe($CodCidade , $AnoMesEmissao, $CnpjEmpresa , $Modelo , $Serie, $NumeroNF, $TipoEmissao){
    $NF8 = "";
    $NF9 = "";
    $Chave = "";
    $Digito = "";

    $tam = strlen($NumeroNF);
    if($tam > 0){
        $NF9 = str_pad($NumeroNF, 9 - $tam, "0", STR_PAD_LEFT); 
        $NF8 = str_pad($NumeroNF, 8 - $tam, "0", STR_PAD_LEFT);
    }else{
        $NF9 = $this->right($NumeroNF, 9);
        $NF8 = $this->right($NumeroNF, 8);
    }

    $Chave = $CodCidade . $AnoMesEmissao . $CnpjEmpresa . $Modelo . $Serie . $NF9 . $TipoEmissao . $NF8;

    $Digito = $this->DigitoMod11($Chave);
    return $Chave . $Digito;
}

My doubt is in the following function:

function right($str, $length) {
    return substr($str, -$length);
}

Function Right does the same as String.Right VB and C#, when searching I didn’t find the same function in php... so I used substr.

The question is, is the substr really the equivalent of the right or is there a function that can replace this method?

Answer 1

The question is, is the substr really the equivalent of the right or is there a function that can replace this method?

Yes, the function substr of php has the same functionality as the function String.Right of Visual Basic. In accordance with documentation of microsoft:

Returns a character string that contains a specified number of characters on the right side of a character string.

An example using the function Right using visual Basic:

Dim TestString As String = "Hello World!"    
Dim subString As String = Right(TestString, 6)
'Saida :  "World!"

Example taken from documentation.

Now, what a documentation of PHP tells about the function replace():

Returns the string part specified by the start and length parameter.

I will not go into detail about the function because that is not the focus of the question.

The same example from above using the language PHP with the function substr() :

$TestString = "Hello World!"    
$subString  = substr($TestString, 6)
//Saida :  "World!"

Completion

The two functions are equivalent and serve basically the same thing.

Note: I recommend reading the documentation of the function replace() because it can receive more parameters than those used here in the answer.