I have a function
void getXFromFile3(FILE* fptr){ double valueX; fscanf(fptr, "%lf\n", &valueX); printf("%lf", valueX); } and file data.dat with some double numbers.
One of them is -0.572869279, but my function print -0.572869. It looks like somewhere my number was cut off.
Any ideas what I am doing wrong?
Tell scanf to tell you how many characters it scanned and then tell printf to print this number of digits after the comma.
Still one needs to take care of sign, and digits before the comma.
The code below assumes leading zeros and no positive signs were in the input.
void getXFromFile3(FILE* fptr){ double x; int n; fscanf(fptr, "%lf%n", &x, &n); printf("%.*lf", /* the l length modifier is optional */ n /* number of characters scanned */ - (x < 0.) /* one off for the minus sign, if any */ - ((int)log10(fabs(x)) + 1) /* off as many as digits before the comma */ - 1, /* one off for the comma */ x); } Hu! ;-)
printf("%.9lf", valueX);(or more) because the default is 6 places.doubleswith different lengths after the decimal. We wouldn't want to print the extra zeros ( probably not the case here) and also what if it has greater than 9 digits sayxdigits? What then?%sand store that as well as processing withsscanf. The answer was: Nothing wrong, the number read is not being cut off.xplaces useprintf("%.*lf", x, valueX);This is a non-question - it's all in theprintfman page.