Dart Number & Dart Int & Dart Double

In Dart, numbers are fundamental for various calculations and data representation. Here's a comprehensive explanation of int, double, and the general num type:

1. int:

• Represents whole (integer) numbers without decimal points.

• Declaration:

Dart

int age = 30;

• Range:

  • The range depends on the platform:

    • Native platforms (mobile/desktop): Typically, -2⁶³ to 2⁶³ - 1.

    • Web platform: Limited to JavaScript's number representation (double-precision floating-point with no fractional part). This effectively restricts the range to -2⁵³ to 2⁵³ - 1.

2. double:

• Represents numbers with decimal points.

• Declaration:

Dart

double pi = 3.14159;

• Storage: Uses 64-bit double-precision floating-point format according to the IEEE 754 standard.

• Precision: Due to the nature of floating-point representation, calculations might involve minor rounding errors.

3. num:

• The base type for both int and double.

• Represents all numeric values.

• Usage:

  • Useful when you need a variable to hold either an integer or a double value:

Dart

    num distance = 10.5; // Can be assigned both int and double values

Key points:

• Type inference: Dart often infers the number type automatically based on the assigned value.

• Conversion:

  • Explicit conversion using toInt() or toDouble() methods:

Dart

    int ageInYears = pi.toInt(); // Truncates decimal part
    double exactAge = ageInYears.toDouble();

Choosing the right type:

• Use int when dealing with whole numbers (e.g., counting, indexing).

• Use double when representing values with decimal precision (e.g., scientific calculations, measurements).

• Use num when the variable might hold either type during the program's execution.

Additional considerations:

• For calculations requiring high precision, explore libraries like dart:math for alternative representations like BigInt.

Resources:

• Numbers in Dart: https://dart.dev/guides/language/numbers

• Built-in types - Dart: https://dart.dev/language/built-in-types

By understanding these data types and their appropriate usage, you can effectively represent numeric data in your Dart applications.