very close. One more idea: typed constants only exist during compilation. In the generated executable they are all typed because they have been used somewhere and that defined their size and type (int, float, ...)
On Wed, Jan 30, 2019 at 6:55 PM 伊藤和也 <[email protected]> wrote: > OK, I understand it somehow but I want to make sure my understanding is > correct. > > There are two types of constant "untyped constant" and "typed constant". > > 1. An untyped constant has a size but it's not specific which means an > untyped constant takes some memory. > >> fmt.Println(100) > > > 2. A typed constant has a specific size which means a typed constant takes > a specific amount of memory. > >> fmt.Println(int(100)) > > > Is my understanding correct? > > 2019年1月31日木曜日 9時05分32秒 UTC+9 伊藤和也: > >> An interger constant is "int" type and takes "8" bytes memory on 64-bit >> system. >> >> fmt.Println(unsafe.Sizeof(100)) // 8 >>> fmt.Println(reflect.TypeOf(100)) // int >> >> >> and an "int32" type value takes "4" bytes. >> >> var num int32 >>> fmt.Println(unsafe.Sizeof(num)) // 4 >> >> >> So in this case below, Is the memory usage "12" bytes in total? (Question >> 1) >> >> var num int32 = 100 >>> | | >>> 4 bytes + 8 bytes = 12 bytes >> >> >> and in this case below, Is the memory usage "16" bytes in total? >> (Question 2) >> because the integer constant "100" is "8" bytes first then it's converted >> to "int32" which is "4" bytes. >> >> var num int32 = int32(100) >>> | | | >>> 4 bytes + 4 bytes + 8 bytes = 16 bytes >> >> -- > You received this message because you are subscribed to the Google Groups > "golang-nuts" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. > -- *Michael T. [email protected] <[email protected]>* -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
