Correct format specifier for double in printf?

Question

What is the correct format specifier for `double` in printf? Is it `%f` or is it `%lf`? I believe it's `%f`, but I am not sure.###Code sample #include int main() { double d = 1.4; printf("%lf", d); // Is this wrong? }

Answer 1

You can use either %g or %f for both floating point numbers and for doubles.

The difference is in the precision with which each prints:

%.3g means you want the total number of significant digits to be 3

%.3f means you want 3 digits after the decimal.

What if you just say %g or %f?

%g will get you 6 sig figs, by default

%f will get you 6 digits after the decimal, by default

Here's the code..............................................

int main(int argc, const char* argv[]) {

double temp_cels = 1234.5678;

printf("temp is: %.3f C, or using sig figs, is: %.3g C\n",

temp_cels, temp_cels);

printf("default case\n");

printf("temp is: %f C, or using sig figs, is: %g C\n",

temp_cels, temp_cels);

return 0;

}

//--------------------------------------------OUTPUT

temp is: 1234.568 C, or using 3 sig figs is: 1.23e+03 C

default case...

temp is: 1234.567800 C, or using default sig figs is: 1234.57 C

Hope that helps!