Getchar

[gilly]

Sorry these may sound like stupid questions but how does getchar work? I know that it reads the data one by one in ASCII code but how can u tell it to store numbers only and print an error message if other characters are used? For an assignment i receive 5 dice values, which are entered, i'm have to display a error message if the numbers are entered with a space between them e.g 1 2 3 4 5 is ok but 1.2.3.4.5 is not. Sorry if this sounds stupid, but i have only just started and help as u can tell.

Thanks for any reply

[Savage]

No,it's not a stupid question.

Here is how getchar works:

getchar() reads from stdin and is line buffered which means that it won't
return anything until you press ENTER.After pressing ENTER it will convert input
to int.

To solve ur problem you will need to search for signs like '.' and others.If any of
them exist you will print out a error.


Savage

[Savage]

Sorry for double post but here is one way:

First you must create array that will contain signs that are not allowed:

char a[15];/*This takes care for signs from 33-47 in ASCII signs.*/
int i,c,good=1;
/*c will represent a variable used by getchar().*/

use for loop to create a array:

for(i=0;i<15;i++) a[i]=33+i;/*This will include signs beetwen 33-47,inclusive.*/

then after using getchar() you must again run same for loop with only one differance it must compare c with possible signs in array.If there is any of them
change good to zero.After that test like:

if(good==0) /*Print error.*/

Note: this will only take care for signs beetwen 33-47,inclusive.I suggest that you use same proces to create more arrays of signs because there is more of
them!!!!.


Savage

[JosAH]

Have a look at the macros

isdigit(x)
isspace(x)

both defined in <ctype.h>

kind regards,

Jos

ps. the getchar() function/macro doesn't do line buffering, nor any buffering
itself at all; it's the stream that does the buffering. stdin is line buffered by
default indeed.

[gilly]

Thank You so much