scanf reads every double wrong

Question

I have the following code:

    int main(void)
{
    double r;
    scanf("lf",&r);
    printf("%lf\n",r);
}

Any value I enter returns a nonsense-number with about 40-50 digits. scanf works fine with chars, integers, strings etc., but with doubles I get this problem. Can anybody help me?

Answer 1

scanf("lf",&r);

Should be

scanf("%lf",&r);

Answer 2

You're missing the percent (%) symbol in the format string, it should be:

scanf("%lf", &r);

and then you should add checking the return value since, as you just learned, I/O is brittle and can fail. Thus, it's wrong to depend on r containing a valid value unless you've verified that the scanning worked:

if(scanf("%lf", &r) == 1)
{
  print("got the double %g\n", r);
}
else
{
  printf("**Failed to read a double value!\n");
}

Answer 3

You need %lf when you read it in.

Answer 4

Try

scanf("%lf",&r);

You forgot to put in the %.

Answer 5

You need

scanf("%lf", &r);

Anytime you use scanf() you need to put the percent sign in front of what type of variable you are using.

Answer 6

You forgot % before lf:

scanf("%lf", &yourDouble);