tolower() and toupper()

[Roman Mashak]

Hello,

what's the point to declare argument to these functions of 'int' type, not
char?

With best regards, Roman Mashak. E-mail: (e-mail address removed)

 

[Guest]

Hello,
[ tolower() and toupper() ]
what's the point to declare argument to these functions of 'int' type, not
char?

This allows you to pass EOF as an argument (which will be returned as
EOF), and in C90 (the most widely supported version C standard), it
also allows you to call these functions without including <ctype.h>.

 

[Roman Mashak]

Hello, Harald!
You wrote on 1 Nov 2006 02:44:50 -0800:

??>> what's the point to declare argument to these functions of 'int' type,
??>> not char?
HvD> This allows you to pass EOF as an argument (which will be returned as
HvD> EOF), and in C90 (the most widely supported version C standard), it
HvD> also allows you to call these functions without including <ctype.h>.
What's the practical necessity to pass EOF?

With best regards, Roman Mashak. E-mail: (e-mail address removed)

 

[Jordan Abel]

Hello, Harald!
You wrote on 1 Nov 2006 02:44:50 -0800:

??>> what's the point to declare argument to these functions of 'int' type,
??>> not char?
HvD> This allows you to pass EOF as an argument (which will be returned as
HvD> EOF), and in C90 (the most widely supported version C standard), it
HvD> also allows you to call these functions without including <ctype.h>.
What's the practical necessity to pass EOF?

while((c = tolower(getchar()))!=EOF) {
...;
}

That's really the weakest reason though, of the ones he gives.

 

[Dik T. Winter]

> Hello,
>
> what's the point to declare argument to these functions of 'int' type, not
> char?

That is to make the following work:
int c1, c2;
while((c1 = getchar()) != EOF) {
c2 = tolower(c1);
}

 

[CBFalconer]

That is to make the following work:
int c1, c2;
while((c1 = getchar()) != EOF) {
c2 = tolower(c1);
}

Which, assuming you need both the values of c1 and c2 preserved, is
more simply written as:

while (EOF != (c2 = tolower(c1 = getchar))) continue;

since the tolower call will preserve the value EOF.

 

[Simon Biber]

Which, assuming you need both the values of c1 and c2 preserved, is
more simply written as:

while (EOF != (c2 = tolower(c1 = getchar))) continue;

since the tolower call will preserve the value EOF.

I think you meant to call getchar, rather than trying to assign a
function pointer to c1. A set of parentheses is missing.

 

[Richard Heathfield]

Simon Biber said:

I think you meant to call getchar, rather than trying to assign a
function pointer to c1. A set of parentheses is missing.

[SFX: rummage rummage]

Aha! ( )

 

[CBFalconer]

I think you meant to call getchar, rather than trying to assign a
function pointer to c1. A set of parentheses is missing.

Thanks for catching that. Should be:
while (EOF != (c2 = tolower(c1 = getchar()))) continue;