1
I have the code below, which accepts values in your inputs and then sends them to the database.
I want that when the user clicks submit, if Cpf is invalid (EX:111.111.111-11), it does not send any value to the database and shows an Alert on the screen indicating that nothing has been added, need an if that has as a condition the valid Cpf, only if the Cpf is valid the values will be sent
Here we have the inputs
	<form action="Dados.php"  method="POST" >
			<table class="table table-striped">
			<thead>
			<tr>
				<th>Nome</th>
				<th>Cpf</th>
				<th>Cep</th>
				<th>Rua</th>
				<th>Bairro</th>
				<th>Cidade</th>
				<th>Estado</th>
				<th>Ibge</th>
				</tr>			
			</thead>
			
			<tbody>
			<tr>
				<td><input type="text" class="form-control input-sm" name="nom" required><br></td>
				
				<td><input type="text" class="form-control input-sm" id="cpf"  name="cpf" required><br></td>
				
				<td><input type="text" class="form-control input-sm" id="cep" name="end" required><br></td>
				
        		<td><input name="rua" class="form-control input-sm" type="text" id="rua" required /><br /></td>
        		
        		<td><input name="bairro" class="form-control input-sm" type="text" id="bairro" required/><br /></td>
        		
        		<td><input name="cidade" class="form-control input-sm" type="text" id="cidade" required/><br /></td>
        		
        		<td><input name="uf" class="form-control input-sm" type="text" id="uf" required/><br /></td>
        	
        		<td><input name="ibge" class="form-control input-sm" type="text" id="ibge" required/><br /></td>
				
			</tr>
			</tbody>
			</table>
			<input type="submit" value="Criar Registro" onclick="function validaCPF()" class="btn btn-default"><input type="button" class="btn btn-warning" value="Voltar"
onclick="window.location='/Banco_de_dados/index.php';"/>
			</form>
And here we have the code that sends the values to the bank
<body>
<?php
//declarando variaveis//
    $servername = 'localhost';
    $username = 'root';
    $password = '';
    $dbname = 'meubd';
    $nome = $_POST['nom'];
    $cpf = $_POST['cpf'];
    $cep = $_POST['end'];
    $rua = $_POST['rua'];
    $bairro = $_POST['bairro'];
    $cidade = $_POST['cidade'];
    $uf = $_POST['uf'];
    $ibge = $_POST['ibge'];
    function validaCPF($cpf = null) {
        // Verifica se um número foi informado
        if(empty($cpf)) {
            return false;
            echo "Cpf";
        }
        // Elimina possivel mascara
        $cpf = ereg_replace('[^0-9]', '', $cpf);
        $cpf = str_pad($cpf, 11, '0', STR_PAD_LEFT);
        // Verifica se o numero de digitos informados é igual a 11
        if (strlen($cpf) != 11) {
            return false;
        }
        // Verifica se nenhuma das sequências invalidas abaixo
        // foi digitada. Caso afirmativo, retorna falso
        else if ($cpf == '00000000000' ||
                $cpf == '11111111111' ||
                $cpf == '22222222222' ||
                $cpf == '33333333333' ||
                $cpf == '44444444444' ||
                $cpf == '55555555555' ||
                $cpf == '66666666666' ||
                $cpf == '77777777777' ||
                $cpf == '88888888888' ||
                $cpf == '99999999999') {
                    return false;
                    // Calcula os digitos verificadores para verificar se o
                    // CPF é válido
                } else {
                    for ($t = 9; $t < 11; $t++) {
                        for ($d = 0, $c = 0; $c < $t; $c++) {
                            $d += $cpf{$c} * (($t + 1) - $c);
                        }
                        $d = ((10 * $d) % 11) % 10;
                        if ($cpf{$c} != $d) {
                            return false;
                        }
                    }
                    return true;
                    $sql = 'INSERT INTO pessoas VALUES ("'.$nome.'", "'.$cpf.'", "'.$cep.'" , "'.$rua.'", "'.$bairro.'", "'.$cidade.'", "'.$uf.'", "'.$ibge.'")';
                    //verificando se os valores foram inseridos//
                    if ($conn->query($sql) === TRUE) {
                        echo "<br>Os valores foram adicionados corretamente";
                    } else {
                        echo "<br>Error: " . $sql . "<br>" . $conn->error;
                    }
                }
    }
//conectando ao banco de dados//verificando conexão//
    $conn = new mysqli($servername, $username, $password, $dbname);
    if ($conn->connect_error) {
        die("Conecxão Falhou: " . $conn->connect_error);
    }
    echo "Conexao foi um sucesso";
//fechando conexão//
    $conn ->close();
?>
</body>
As I mentioned before, there may be many errors in my code, so I ask for your help.
There is an API ready for this type of validations, just import from Maven, follow the [link][1] [1]: https://github.com/jereztech/validation-br-api
– J. Jerez