20+ mejores Interview Questions and Answers (2024)

Pregunta 1

What does a special set of tags <?= and ?> do in PHP?

The output is displayed directly to the browser.

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Pregunta 2

Would I use print "$a dollars" or "{$a} dollars" to print out the amount of dollars in this example?

In this example it wouldn't matter, since the variable is all by itself, but if you were to print something like "{$a},000,000 mln dollars", then you definitely need to use the braces.

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Pregunta 3

How do you define a constant?

Via define() directive, like define ("MYCONSTANT", 100);

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Pregunta 4

How do you pass a variable by value?

Just like in C++, put an ampersand in front of it, like $a = &$b

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Pregunta 5

When are you supposed to use endif to end the conditional statement?

When the original if was followed by : and then the code block without braces.

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Pregunta 6

Explain the ternary conditional operator in PHP?

Expression preceding the ? is evaluated, if it's true, then the expression preceding the : is executed, otherwise, the expression following : is executed.
E.g $id = isset($_GET['id']) ? $_GET['id'] : false;

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Pregunta 7

How do you call a constructor for a parent class?

parent::constructor($value)

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Pregunta 8

Why doesn't the following code print the newline properly? �� $str = 'Hello, there.nHow are you?
�� print $str;
�� ?>

Because inside the single quotes the n character is not interpreted as newline, just as a sequence of two characters - and n.

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Pregunta 9

Would you initialize your strings with single quotes or double quotes?

Since the data inside the single-quoted string is not parsed for variable substitution, it's always a better idea speed-wise to initialize a string with single quotes, unless you specifically need variable substitution.

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Pregunta 10

What is the difference between characters 23 and x23?

The first one is octal 23, the second is hex 23.

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Pregunta 11

I want to combine two variables together:

 $var1 = 'Welcome to '; $var2 = 'TechInterviews.com';

What will work faster? Code sample 1: -
$var 3 = $var1.$var2;
Or code sample 2:
$var3 = "$var1$var2";
Both examples would provide the same result - $var3 equal to "Welcome to TechInterviews.com". However, Code Sample 1 will work significantly faster. Try it out with large sets of data (or via concatenating small sets a million times or so), and you will see that concatenation works significantly faster than variable substitution.

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Pregunta 12
For printing out strings, there are echo, print and printf. Explain the differences.

echo is the most primitive of them, and just outputs the contents following the construct to the screen. print is also a construct (so parentheses are optional when calling it), but it returns TRUE on successful output and FALSE if it was unable to print out the string. However, you can pass multiple parameters to echo, like:
<?php echo 'Welcome ', 'to', ' ', 'TechInterviews!'; ?>
and it will output the string "Welcome to TechInterviews!" print does not take multiple parameters. It is also generally argued that echo is faster, but usually the speed advantage is negligible, and might not be there for future versions of PHP. printf is a function, not a construct, and allows such advantages as formatted output, but it's the slowest way to print out data out of echo, print and printf.

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Interview Questions and Answers

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Preguntas y respuestas para nivel principiante / recien graduados

What does a special set of tags <?= and ?> do in PHP?

Guardar para repaso

Would I use print "$a dollars" or "{$a} dollars" to print out the amount of dollars in this example?

Guardar para repaso

How do you define a constant?

Guardar para repaso

How do you pass a variable by value?

Guardar para repaso

When are you supposed to use endif to end the conditional statement?

Guardar para repaso

Explain the ternary conditional operator in PHP?

Guardar para repaso

How do you call a constructor for a parent class?

Guardar para repaso

Why doesn't the following code print the newline properly? �� $str = 'Hello, there.nHow are you?
�� print $str;
�� ?>

Guardar para repaso

Would you initialize your strings with single quotes or double quotes?

Guardar para repaso

What is the difference between characters 23 and x23?

Guardar para repaso

I want to combine two variables together:

Guardar para repaso

For printing out strings, there are echo, print and printf. Explain the differences.

Guardar para repaso

Lo mas util segun los usuarios:

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Temas de entrevista relacionados

Todos los temas de entrevista

WithoutBook

Desarrolla tus habilidades con rutas de aprendizaje enfocadas, examenes de practica y contenido listo para entrevistas.

Interview Questions and Answers

La mejor entrevista simulada en vivo que deberias ver antes de una entrevista

Interview Questions and Answers

Preguntas y respuestas para nivel principiante / recien graduados

What does a special set of tags <?= and ?> do in PHP?

Guardar para repaso

Would I use print "$a dollars" or "{$a} dollars" to print out the amount of dollars in this example?

Guardar para repaso

How do you define a constant?

Guardar para repaso

How do you pass a variable by value?

Guardar para repaso

When are you supposed to use endif to end the conditional statement?

Guardar para repaso

Explain the ternary conditional operator in PHP?

Guardar para repaso

How do you call a constructor for a parent class?

Guardar para repaso

Why doesn't the following code print the newline properly? ��� ����������� $str = 'Hello, there.nHow are you?����������� print $str;��� ?>

Guardar para repaso

Would you initialize your strings with single quotes or double quotes?

Guardar para repaso

What is the difference between characters 23 and x23?

Guardar para repaso

I want to combine two variables together:

Guardar para repaso

For printing out strings, there are echo, print and printf. Explain the differences.

Guardar para repaso

Lo mas util segun los usuarios:

Diferencias relacionadas

Temas de entrevista relacionados

Todos los temas de entrevista

WithoutBook

Why doesn't the following code print the newline properly? �� $str = 'Hello, there.nHow are you?
�� print $str;
�� ?>