notANumber in C? how?

[delta770]

i've done VB programming, and java, but i'm new to C, and i was wondering how i would be able to read a valid input.

if the user inputs an invalid number, how do i check for that? java there is a command called notANumber returns a boolean, (or something very similar)...is there an equivalent in c?


also is there a way to check if the int entered is too large? i'm trying to do something using "sizeof()", but not sure what i can do with it...
any other functions or expressions i could use?



i'm trying to stay away from trying and catching exceptions...
thanx in advance

--770

[RabidChimp]

<cctype> // C++
<ctype.h> /* C */

int isalnum(int c);
int isalpha(int c);
int isblank(int c); [added with C99]
int iscntrl(int c);
int isdigit(int c);
int isgraph(int c);
int islower(int c);
int isprint(int c);
int ispunct(int c);
int isspace(int c);
int isupper(int c);
int isxdigit(int c);
int tolower(int c);
int toupper(int c);

isalnum

int isalnum(int c);

The function returns nonzero if c is any of:

a b c d e f g h i j k l m n o p q r s t u v w x y z
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
0 1 2 3 4 5 6 7 8 9

or any other locale-specific alphabetic character.
isalpha

int isalpha(int c);

The function returns nonzero if c is any of:

a b c d e f g h i j k l m n o p q r s t u v w x y z
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or any other locale-specific alphabetic character.
isblank

int isblank(int c); [added with C99]

The function returns nonzero if c is any of:

HT space

or any other locale-specific blank character.
iscntrl

int iscntrl(int c);

The function returns nonzero if c is any of:

BEL BS CR FF HT NL VT

or any other implementation-defined control character.
isdigit

int isdigit(int c);

The function returns nonzero if c is any of:

0 1 2 3 4 5 6 7 8 9

isgraph

int isgraph(int c);

The function returns nonzero if c is any character for which either isalnum or ispunct returns nonzero.
islower

int islower(int c);

The function returns nonzero if c is any of:

a b c d e f g h i j k l m n o p q r s t u v w x y z

or any other locale-specific lowercase character.
isprint

int isprint(int c);

The function returns nonzero if c is space or a character for which isgraph returns nonzero.
ispunct

int ispunct(int c);

The function returns nonzero if c is any of:

! " # % & ' ( ) ; <
= > ? [ \ ] * + , -
. / : ^ _ { | } ~

or any other implementation-defined punctuation character.
isspace

int isspace(int c);

The function returns nonzero if c is any of:

CR FF HT NL VT space

or any other locale-specific space character.
isupper

int isupper(int c);

The function returns nonzero if c is any of:

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or any other locale-specific uppercase character.
isxdigit

int isxdigit(int c);

The function returns nonzero if c is any of:

0 1 2 3 4 5 6 7 8 9 a b c d e f A B C D E F

tolower

int tolower(int c);

The function returns the corresponding lowercase letter if one exists and if isupper(c); otherwise, it returns c.
toupper

int toupper(int c);

The function returns the corresponding uppercase letter if one exists and if islower(c); otherwise, it returns c.

from CodeGoddess


Hope this helps

[delta770]

where did you get this??

is there an online api for c anywhere?

thanx for your help

-770

[CornedBee]

Lots. Search Google for CRT and reference.