Re: how to check the scanf function if it will read more than one number


Keith Thompson wrote:
> scanf() returns the number of items assigned. If you give it " 32 a ",
> it will assign 32 to dend and fail to assign a value to dor; scanf()
> will then return 1. If you want to assign both values, you need to
> check whether scanf() returned 2.
>
> You should pick a better name than "temp1". The simplest thing to do

sorry,because I copied it from a long code,
if I named every variant with its meaning, there must be too many
temporary variants.
so ......

> is to assign the result of scan() to a variable, and test the value
> of that variable. Pseudo-code follows:
>
> do {
> printf("...\n");
> items_read = scanf(...);
> } while (items_read != 2);
>
> Don't use fflush(stdin). The fflush() function is defined only for
> output streams.


Thanks very much!!
but I don't know very clearly why shouldn't I use the fflush function.
if there is not any usable data in the input stream,
could I use it to clear the input stream?
if not , could you please tell me why?


> scanf() can be very tricky, it can leave unread garbage in your input
> stream, and it can be difficult to figure out just what it's doing. A
> better approach is to use fgets() to read an entire line, then use
> sscanf() to get information from the line you've read.

thanks for your suggestion!


> --
> Keith Thompson (The_Other_Keith) kst-u@xxxxxxx <http://www.ghoti.net/~kst>
> San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
> We must do something. This is something. Therefore, we must do this.

.

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