flushing input buffer

[mac23]

Is there any way to flush the input buffer? The problem where I faced it will make it clear what I want exactly.

main(){

	char buffer[20];
	
	scanf(“%s”, buffer);
	getchar();

}

Since the scanf does not take in the newline when the enter key is pressed, it remains in the buffer which is taken by getchar(); thus it does not wait for user input anymore. Of course this problem can be solved by replacing scanf with functions such as gets() or similar function as follows:-

main(){

	char buffer[20];
	
	gets(buffer);
	getchar();

}

But I want to know if there is any way to flush the input buffer. fflush () works for output stream not input; aren’t there any equivalent function for input stream?

[abcde]

Originally Posted by mac23

Is there any way to flush the input buffer? fflush () works for output stream not input; aren’t there any equivalent function for input stream?

If I want to zap to a newline, I getchar() all the characters until I get EOF or a newline:

int main() {

	char buffer[20];
	int ch;
	
	scanf(“%s”, buffer);
	while ((ch = getchar()) && ch != '\n' && ch != EOF) { /* do nothing */ }

}

Originally Posted by mac23

Of course this problem can be solved by replacing scanf with functions such as gets()

Just a warning: gets() is dangerous (re: buffer overflows) and you should get a warning if you use it. Use fgets() as it is safe.

[sheep]

#include <stdio.h>

int main(int argc, char **argv)
{
        char buf[256];
        fscanf(stdin, "%s", buf);
        return 0;
}

Do NOT use gets(). EVER.

Also: http://c-faq.com/stdio/stdinflush.html and this: http://c-faq.com/stdio/stdinflush2.html .

[mac23]

thanks to both of u. indeed i used to get a warning that gets is dangerous.