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This page covers automatic type conversion rules and behavior in Simple Issue Language (SIL™), distinct from explicit type casting.

// Number conversion examples
number n1 = "42";     // String to number: 42.0
number n2 = 42;       // Integer to number: 42.0

// Integer conversion examples
integer i1 = "123";   // String to integer: 123
integer i2 = 123.7;   // Number to integer: 123 (truncated)

// Boolean conversion examples
boolean b1 = "true";  // String to boolean: true
boolean b2 = 1;       // Number to boolean: true
boolean b3 = 0;       // Number to boolean: false

//Byte conversion examples
byte b1 = (byte) "123";    // String to byte: 123 (if within byte range -128 to 127)
byte b2 = (byte) "-128";   // String to byte: 56 (minimum byte value)
byte b3 = (byte) 123.7;    // Number to byte: 123 (decimal part truncated)
byte b4 = (byte) -5.9;     // Number to byte: -5 (decimal part truncated)
byte b5 = (byte) 200;      // Integer to byte: -56 (wraps around from 200 to -56)
byte b6 = (byte) -200;     // Integer to byte: 56 (wraps around from -200 to 56)

// Date conversion examples
date d1 = "2024-01-01";        // String to date
date d2 = 1704067200000;       // Milliseconds to date

// Interval conversion examples
interval iv1 = "1h 30m";       // String to interval
interval iv2 = 5400000;        // Milliseconds to interval

Casting a string to an array is a two-step process:

• First, the strings transformed to a string[] by splitting it at every character with a |.

• The conversion is done from string[] to the target array type.

// Example 1: Number Array to String Array (Valid)
number[] numbers = [1, 2.5, 3.7, -4.2];
string[] stringNumbers = numbers;    // Valid conversion
// Result: ["1", "2.5", "3.7", "-4.2"]

// Example 2: Date Array to Interval Array (Invalid)
date[] dates = [
    "2024-01-01",
    "2024-01-02",
    "2024-01-03"
];
// interval[] periods = dates;    // This would cause a conversion error
                                 // Error: Cannot convert date to interval

// Step 1: "1|2|3" → ["1", "2", "3"]
// Step 2: ["1", "2", "3"] → [1, 2, 3]

// Basic number array conversion
string numericString = "1|2|3|4|5";
number[] numbers = numericString;
// Result: [1.0, 2.0, 3.0, 4.0, 5.0]

// Basic boolean array conversion
string boolString = "true|false|true|true";
boolean[] flags = boolString;
// Result: [true, false, true, true]

Casting a structure to a string is equivalent to casting to a string[], and then the resulting array to string.

// Define a simple structure
struct Person {
    string name;
    integer age;
    boolean isActive;
}

// Create and convert instance
Person person = { "John Smith", 30, true};

// Direct conversion to string
string personString = person;
return personString;
// Result: John Smith|30|true

// Structure with all number fields
struct Point3D {
    number x;
    number y;
    number z;
}

Point3D point = { 1.5, 2.0, 3.5 };

// Convert to number array (valid because all fields are numbers)
number[] coordinates = point;
// Result: [1.5, 2.0, 3.5]

// Convert to string array (always valid as all types can convert to string)
string[] stringCoords = point;
return stringCoords;
// Result: 1.5|2|3.5

// Simple structure with a single numeric value
struct Temperature {
    number value;
}

// Create instance
Temperature temp = { 25.5 };

// GOAL: Convert the structure to a number

// Invalid: Direct conversion
// number n = temp;    // Error: Cannot convert structure to number

// Valid: Multi-step conversion
string tempStr = temp;           // Step 1: Structure to string ("25.5")
number tempValue = tempStr;      // Step 2: String to number (25.5)

// Alternative using array
string[] tempArray = temp;       // Step 1: Structure to string array (["25.5"])
number tempValue2 = tempArray[0];// Step 2: First array element to number (25.5)

// Using explicit casts (more verbose but clearer)
number explicitValue = (number)((string)temp);

function f(string s){
    print(s);
}
f(2); //number automatically converted to string
f(true); // boolean automatically converted to string