Mikroelektronika MIKROE-724 データシート

214

mikoBasic PRO for dsPIC30/33 and PIC24

MikroElektronika

Conversion of variable of one type to a variable of another type is typecasting. mikroBasic PRO for dsPIC30/33 and 

PIC24 supports both implicit and explicit conversions for built-in types.

Implicit Conversion

Compiler will provide an automatic implicit conversion in the following situations:

 

- statement requires an expression of particular type (according to language definition) and we use an  

 

  expression of different type, 

 

- operator requires an operand of particular type and we use an operand of different type, 

 

- function requires a formal parameter of particular type and we pass it an object of different type, 

 

- 

result

 does not match the declared function return type. 

When operands are of different types, implicit conversion promotes the less complex type to more complex type taking 

the following steps:

bit       →  byte/char

byte/char →  word

short     →  integer

short     →  longint

integer   →  longint

integral  →  float

Higher bytes of extended unsigned operand are filled with zeroes. Higher bytes of extended signed operand are filled 

with bit sign (if number is negative, fill higher bytes with one, otherwise with zeroes). For example:

dim a as byte

dim b as word

‘...

a = $FF

b = a  ‘ a is promoted to word, b becomes $00FF

In assignments and statements that require an expression of particular type, destination will store the correct value only 

if it can properly represent the result of expression, i.e. if the result fits in destination range.

If expression evaluates to a more complex type than expected, excess of data will be simply clipped (higher bytes are 

lost).

dim i as byte

dim j as word

‘...

j = $FF0F

i = j  ‘ i becomes $0F, higher byte $FF is lost