Question

We want to ensure that upto 10 decimal point values are kept while converting a double value to a string.

When we tried %e or %f, it will not keep more than 5 decimal points.
When we tried %.14f, the small values (less than 1.0e-20) are not properly converted to string.

What format string to be used to keep upto 10 decimal points for double values?

Answer 1

Try %.17g to print with the most appropriate format for the double in question.

printf("%.17g\n", 10000.);
printf("%.17g\n", 240.0008);
printf("%.17g\n", 0.0000000013);

10000
240.0008
1.3000000000000001e-009