conversion, promotion, exact match

Andy

Hi...

i'm trying to understand the concept of function name overloading in
c++.
to understand the resolving system it's important to understand the
diffrent
levels of typecasting (exact match, promotion, conversion, not
possible)

that is, what i don't really understand. so i tried do make a little
table:

| bool | char | unsig int | int | float | double
-----------------------------------------------------------
bool into | EM | PRO | PRO | PRO | |
-----------------------------------------------------------
char into | | EM | PRO | PRO | PRO | PRO
-----------------------------------------------------------
unsig into | | | EM | | |
-----------------------------------------------------------
int into | CON | CON | | EM | CON | CON
-----------------------------------------------------------
float into | | | | | EM | PRO
-----------------------------------------------------------
double into| CON | | | | | EM

(e.g.: float into double: PRO)
EM= exakt match
PRO= promotion
CON= conversion
NP= not possible

it would be a great help for me if someone could correct and complete
this table.

thanks a lot...

andy

Sep 7 '05 #1

Subscribe Post Reply

2142

Andy

Andy schrieb:

Hi...

i'm trying to understand the concept of function name overloading in
c++.
to understand the resolving system it's important to understand the
diffrent
levels of typecasting (exact match, promotion, conversion, not
possible)

that is, what i don't really understand. so i tried do make a little
table:

| bool | char | unsig int | int | float | double
-----------------------------------------------------------
bool into | EM | PRO | PRO | PRO | |
-----------------------------------------------------------
char into | | EM | PRO | PRO | PRO | PRO
-----------------------------------------------------------
unsig into | | | EM | | |
-----------------------------------------------------------
int into | CON | CON | | EM | CON | CON
-----------------------------------------------------------
float into | | | | | EM | PRO
-----------------------------------------------------------
double into| CON | | | | | EM

(e.g.: float into double: PRO)
EM= exakt match
PRO= promotion
CON= conversion
NP= not possible

it would be a great help for me if someone could correct and complete
this table.

sorry for being impatient, but i'm just wondering why nobody answers to
my post.
is it useless to make a table like intended to do, or did i violate a
rule and my post is not as post need to be in this group?

please answer me!

Sep 10 '05 #2

John Harrison

Andy wrote:

Andy schrieb:

Hi...

i'm trying to understand the concept of function name overloading in
c++.
to understand the resolving system it's important to understand the
diffrent
levels of typecasting (exact match, promotion, conversion, not
possible)

that is, what i don't really understand. so i tried do make a little
table:

| bool | char | unsig int | int | float | double
-----------------------------------------------------------
bool into | EM | PRO | PRO | PRO | |
-----------------------------------------------------------
char into | | EM | PRO | PRO | PRO | PRO
-----------------------------------------------------------
unsig into | | | EM | | |
-----------------------------------------------------------
int into | CON | CON | | EM | CON | CON
-----------------------------------------------------------
float into | | | | | EM | PRO
-----------------------------------------------------------
double into| CON | | | | | EM

(e.g.: float into double: PRO)
EM= exakt match
PRO= promotion
CON= conversion
NP= not possible

it would be a great help for me if someone could correct and complete
this table.

sorry for being impatient, but i'm just wondering why nobody answers to
my post.
is it useless to make a table like intended to do, or did i violate a
rule and my post is not as post need to be in this group?

please answer me!

You didn't violate any rules, I guess no-one found your topic
interesting or important enough to answer.

The C++ standard actually allows some leeway to implementors so I don't
think you can write one table that would work for all implementations.
For instance char -> unsigned int is a conversion if char is signed but
a promotion if char is unsigned.

Your table has some mistakes, bool to char is a conversion for instance,
There are no promotions to char. char to unsigned int may be a promotion
or a conversion, as explained above.

All the blanks in your table are conversions.

Hopefully that gives you enough information to complete the table.

john

Sep 10 '05 #3

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