How do parseInt() and Number() differ in their approaches to string conversion?

Distinguishing parseInt() from Number(): Semantic Differences and Numerical Conversion

Question:

How do parseInt() and Number() differ in their approaches to converting strings into numerical values?

Answer:

While both parseInt() and Number() aim to extract numbers from strings, they possess fundamental semantic differences.

• parseInt() Performs Parsing:

parseInt() is primarily utilized for parsing strings, attempting to extract numeric values based on the specified radix. Radix represents the base of the number system, such as decimal (base 10) or hexadecimal (base 16). By default, parseInt() assumes decimal radix.

• Number() Performs Type Conversion:

Unlike parseInt(), Number() acts as a function to perform type conversion, converting a given string to a numeric value. This conversion process considers various factors, including exponential notation, octal notation, and hexadecimal notation.

Conversion Behavior:

• Base Radix:

  • parseInt() interprets strings assuming a specific radix. For instance, parseInt("10100", 2) would be interpreted as 20 using a binary radix (base 2).
  • Number() does not have explicit radix interpretation capabilities. It recognizes octal notation (e.g., "0o10") explicitly, treating it as a base 8 number.

• Trailing Characters:

  • parseInt() ignores trailing characters that do not correspond to valid digits under the specified radix.
  • Number() interprets trailing characters as part of the number.

• Implicit Octals:

  • Number() cannot detect implicit octal notations (e.g., "010"), but it can detect explicit ones (e.g., "0o10").
  • parseInt() interprets "010" as an octal number (base 8) unless specified otherwise with an alternative radix.

• Hexadecimal Notation:

  • Both parseInt() and Number() can convert strings in hexadecimal notation, using a radix of 16 (e.g., parseInt("0xF") = 15).

• Equivalent Type Conversion:

  • The unary plus operator ( ) can also be used for numeric type conversion, acting similarly to Number() as a function (e.g., "2e1" = 20).

The above is the detailed content of How do parseInt() and Number() differ in their approaches to string conversion?. For more information, please follow other related articles on the PHP Chinese website!