scanf is collecting the wrong input

Question

 #include 
 int main(void)
 {
      double c;
      scanf(\"%f\", &c);
      printf(\"%f\", c);
 }

This is an exerpt from a program

Answer 1

You need to use "%lf" for double.

This is the warning from clang compiler.

warning: format specifies type 'float *' but the argument has type 'double *' [-Wformat] scanf("%f", &c);

Here is the scanf reference. It's format is %[*][width][length]specifier. The specifier for 'floating point number' is f. So we use %f to read float x. To read double x, we need to specify the length as l. Combined the format is %lf.