Gettype and typeof checks in PHP - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of gettype() for a float?

Consider the following PHP code:

$value = 3.14;
echo gettype($value);

What will be printed?

PHP

$value = 3.14;
echo gettype($value);

A "double"

B "float"

C "decimal"

D "real"

💡 Hint

PHP uses a specific string for floating point numbers in gettype().

In PHP 7.2 and later, gettype() returns "float" for floating point numbers, not "double" or other variants.

❓ Predict Output

intermediate

What does gettype() return for a boolean false?

Given this PHP code:

$flag = false;
echo gettype($flag);

What is the output?

PHP

$flag = false;
echo gettype($flag);

A "bool"

B "false"

C "boolean"

D "bit"

💡 Hint

PHP uses a full word for boolean types in gettype().

gettype() returns "boolean" for both true and false values in PHP.

❓ Predict Output

advanced

What is the output of this gettype check in PHP?

Analyze this PHP snippet:

$var = 42;
if (gettype($var) === 'integer') {
    echo 'Integer!';
} else {
    echo 'Not integer';
}

What will be printed?

PHP

$var = 42;
if (gettype($var) === 'integer') {
    echo 'Integer!';
} else {
    echo 'Not integer';
}

A Integer!

B Syntax error

C Not integer

D Runtime error

💡 Hint

Check the exact string returned by gettype() for integers.

gettype() returns "integer" for integer values. The strict comparison === 'integer' matches, so 'Integer!' is printed.

❓ Predict Output

advanced

What error does this typeof check cause?

Look at this PHP code:

$value = 'hello';
if (typeof($value) === 'string') {
    echo 'It is a string';
} else {
    echo 'Not a string';
}

What happens when this code runs?

PHP

$value = 'hello';
if (typeof($value) === 'string') {
    echo 'It is a string';
} else {
    echo 'Not a string';
}

A Warning: Invalid argument

B Not a string

C It is a string

D Fatal error: undefined function typeof()

💡 Hint

Check if typeof() is a valid PHP function.

PHP does not have a typeof() function. Using it causes a fatal error about undefined function.

🧠 Conceptual

expert

Which statement about gettype() in PHP is TRUE?

Select the correct statement about the behavior of gettype() in PHP.

A gettype() returns 'boolean' for both true and false values.

B gettype() returns 'string' for null values.

C gettype() returns 'float' for floating point numbers.

D gettype() returns 'int' for integer values.

💡 Hint

Recall the exact strings gettype() returns for different types.

gettype() returns 'boolean' for true and false, 'integer' for integers, 'float' for floats, and 'NULL' for null values.

Practice

1. What does the PHP function gettype() return when called on a variable?

easy

A. A string describing the variable's type

B. An integer representing the type code

C. A boolean indicating if the variable is set

D. An object describing the variable

Solution

1. Step 1: Understand the purpose of gettype()

   The gettype() function returns the type of a variable as a string, such as "integer", "string", or "array".

2. Step 2: Compare options with gettype() behavior

   The option stating that it returns a string describing the variable's type is correct.

3. Final Answer:

   A string describing the variable's type -> Option A

4. Quick Check:

   gettype() = string description [OK]

Hint: Remember: gettype() always returns a string type name [OK]

Common Mistakes:

• Thinking gettype() returns a numeric code
• Confusing gettype() with isset()
• Assuming gettype() returns an object

2. Which of the following is the correct syntax to get the type of a variable $var using gettype() in PHP?

easy

A. gettype $var;

B. typeof $var;

C. typeof($var);

D. gettype($var);

Solution

1. Step 1: Recall correct function syntax in PHP

   PHP functions require parentheses around arguments, so gettype($var); is correct syntax.

2. Step 2: Check other options for syntax errors

   Syntax using typeof is invalid because it is not a PHP function. gettype $var; misses parentheses, which is invalid syntax.

3. Final Answer:

   gettype($var); -> Option D

4. Quick Check:

   Function call syntax = gettype($var) [OK]

Hint: Use parentheses with function calls in PHP [OK]

Common Mistakes:

• Using typeof instead of gettype()
• Omitting parentheses in function calls
• Confusing PHP syntax with JavaScript

3. What will be the output of the following PHP code?

$x = 3.14;
echo gettype($x);

medium

A. integer

B. double

C. float

D. string

Solution

1. Step 1: Identify the variable type

   The variable $x is assigned 3.14, which is a floating-point number.

2. Step 2: Understand gettype() output for floats

   In PHP, gettype() returns "double" for floating-point numbers, not "float".

3. Final Answer:

   double -> Option B

4. Quick Check:

   gettype(3.14) = double [OK]

Hint: Remember: PHP calls floats "double" in gettype() output [OK]

Common Mistakes:

• Expecting output to be "float" instead of "double"
• Confusing integer and float types
• Assuming gettype() returns "string" for numbers

4. Consider this PHP code snippet:

$value = true;
if (typeof($value) === 'boolean') {
    echo 'Boolean type';
} else {
    echo 'Not boolean';
}

What is the problem with this code?

medium

A. typeof is not a valid PHP function

B. Comparison operator === cannot be used with strings

C. Boolean values cannot be checked with typeof

D. The variable $value is not defined

Solution

1. Step 1: Check if typeof is a PHP function

   PHP does not have a built-in typeof() function; it uses gettype() instead.

2. Step 2: Analyze the impact of using typeof()

   Using typeof() causes a fatal error because the function does not exist.

3. Final Answer:

   typeof is not a valid PHP function -> Option A

4. Quick Check:

   typeof() invalid in PHP [OK]

Hint: Use gettype(), not typeof(), in PHP [OK]

Common Mistakes:

• Assuming typeof() exists in PHP like in JavaScript
• Thinking === cannot compare strings
• Ignoring variable initialization

5. In PHP 8.0+, the typeof operator returns a Type object instead of a string. Given this code:

$var = [1, 2, 3];
$type = typeof $var;
echo $type->name;

What will be the output?

hard

A. Type

B. object

C. error

D. array

Solution

1. Step 1: Verify typeof in PHP 8.0+

   PHP has no typeof operator or function in 8.0+ or any version; use gettype() instead.

2. Step 2: Predict code execution

   The undefined typeof causes a fatal error (e.g., "Call to undefined function"). No echo output.

3. Final Answer:

   error -> Option C

4. Quick Check:

   typeof invalid in PHP [OK]

Hint: PHP has no typeof; use gettype() [OK]

Common Mistakes:

• Believing typeof exists in PHP 8.0+
• Confusing PHP with JavaScript's typeof
• Expecting a Type object return