[c] 'sprintf': double precision in C

Consider:

double a = 0.0000005l;
char aa[50];
sprintf(aa, "%lf", a);
printf("%s", aa);

Output: s0.000000

In the above code snippet, the variable aa can contain only six decimal precision. I would like to get an output like "s0.0000005". How do I achieve this?

The problem is with sprintf

sprintf(aa,"%lf",a);

%lf says to interpet "a" as a "long double" (16 bytes) but it is actually a "double" (8 bytes). Use this instead:

sprintf(aa, "%f", a);

More details here on cplusplus.com

You need to write it like sprintf(aa, "%9.7lf", a)

Check out http://en.wikipedia.org/wiki/Printf for some more details on format codes.