cscanfconversion-specifier

Reading in double values with scanf in c

I try to read-in 2 values using scanf() in C, but the values the system writes into memory are not equal to my entered values. Here is the code:

double a,b;
printf("--------\n"); //seperate lines
scanf("%ld",&a);
printf("--------\n"); 
scanf("%ld",&b);
printf("%d %d",a,b);

If I enter 1 and 2, CMD returns a correct, but b = -858993460 Here is what I already tried: using float or int instead of double, using scanf_s, using scanf("%d or %f for %i or %li or %lf or %e or %g ), using fflush(stdin) to clear keyboard buffer, reading in b first, trying like all possible combinations. I found out that there is a problem with the length of double on 32 bit OS, so that you are forced to use scanf("%lf", &f) to read in a double. No matter what I do, second value is always wrong.

I use MS VS express 2012 for Desktop on Windows 7 32 bit OS.

Solution

  • Use the %lf format specifier to read a double:

    double a;
scanf("%lf",&a);

    Wikipedia has a decent reference for available format specifiers.

    You'll need to use the %lf format specifier to print out the results as well:

    printf("%lf %lf",a,b);