50% developed

D (The Programming Language)/d2/Type Conversion

From Wikibooks, open books for an open world
Jump to navigation Jump to search

Lesson 5: Type Conversion

[edit | edit source]

In this lesson, you will learn how the types of variables can be implicitly and explicitly converted.

Introductory Code

[edit | edit source]
import std.stdio;
void main()
    short a = 10;
    int b = a;
    // short c = b;
    // Error:  cannot implicitly convert 
    // expression b of type int to short
    short c = cast(short)b;
    char d = 'd';
    byte e = 100;
    wchar dw = 'd';
    int f = d + e + dw;
    writeln(f); //300
    float g1 = 3.3;
    float g2 = 3.3;
    float g3 = 3.4;
    int h = cast(int)(g1 + g2 + g3);
    writeln(h); //10
    int i = cast(int)g1 + cast(int)g2 + cast(int)g3;
    writeln(i); //9


[edit | edit source]

Implicit Integral Conversions

[edit | edit source]

An object of an integral type can be converted to another object of an integral type as long as the destination type is wider than the original type. These conversions are implicit:


Explicit Conversions

[edit | edit source]

Casting is a way to tell the compiler to try to force an object to change type. In D, you do this by writing cast(type).

  • You cannot convert an integral value to a string (or the other way around) with a cast. There is a library function which you will learn later for that.