scanf problems

[Unregistered]

I am trying to write a program for my C programming class and I cannot get scanf("%c") to work. The program doesn't wait for the user to enter a character before continuing. If someone could please help me soon I would be so happy. the program si due in 3 hours.

Thank you so much!

[vsriharsha]

Hi,
try including the statement

fflush(stdin);


before the scanf() statement and I guess ur problem should be solved.
Regards,

[C_Coder]

Hi,
try including the statement

fflush(stdin);

NO, the result of fflush is undefined for input streams.
Use:

while(getchar() != '\n');

A better idea would be to never use scanf again.

[PutoAmo]

Dear Unregistered,

Problem is that scanf() will read from standard input (most often keyboard) until it finds a newline character (the 'enter' key). When it finally finds the newline character, it doesn't take it with the rest of the data to be formatted !! Instead, it is left in the input stream !! When next scanf() in program is processed it will read that newline character left from former scanf() and put it in the first variable in the variable list. Exemple :

scanf ("%d", &a_number);

scanf ("%c", &a_character);

In this case, the newline charater by first scanf() in input buffer will be put in a_character by second scanf(). We can avoid this inconvenience by means of a space character in format string in second scanf(), right befor %c. Or we can just use a function, like getchar() that "eats" that newline character.

scanf ("%d", &a_number);

scanf (" %c", &a_character);    /* space character before %c */

or ...

scanf ("%d", &a_number);

while (getchar() != '\n');   /* usually implemented this way */

scanf ("%c", &a_character);

[Prelude]

>We can avoid this inconvenience by means of a space character in format string in second scanf(),
Another alternative is to place a newline in the format string of the first call to scanf:

scanf ( "%d\n", &i );
scanf ( "%c", &ch );
printf ( "%d %c\n", i, ch );

The number of ways to get around the bugs alone should teach you not to use scanf, it's just plain dangerous if you don't know how it works.

-Prelude