printf and long double

Question

I am using the latest gcc with Netbeans on Windows. Why doesn't long double work? Is the printf specifier %lf wrong?

Code:

#include <stdio.h>

int main(void)
{
    float aboat = 32000.0;
    double abet = 5.32e-5;
    long double dip = 5.32e-5;

    printf("%f can be written %e\n", aboat, aboat);
    printf("%f can be written %e\n", abet, abet);
    printf("%lf can be written %le\n", dip, dip);

    return 0;
}

Output:

32000.000000 can be written 3.200000e+004
0.000053 can be written 5.320000e-005
-1950228512509697500000000000000000000000000000000000000000000000000000000000000
000000000000000000000000000000000000000000000000000000000000000000000000.000000
can be written 2.725000e+002
Press [Enter] to close the terminal ...

Answer 1

Was having this issue testing long doubles, and alas, I came across a fix! You have to compile your project with -D__USE_MINGW_ANSI_STDIO:

Jason Huntley@centurian /home/developer/dependencies/Python-2.7.3/test $ gcc main.c

Jason Huntley@centurian /home/developer/dependencies/Python-2.7.3/test $ a.exe c=0.000000

Jason Huntley@centurian /home/developer/dependencies/Python-2.7.3/test $ gcc main.c -D__USE_MINGW_ANSI_STDIO

Jason Huntley@centurian /home/developer/dependencies/Python-2.7.3/test $ a.exe c=42.000000

Code:

Jason Huntley@centurian /home/developer/dependencies/Python-2.7.3/test
$ cat main.c
#include <stdio.h>

int main(int argc, char **argv)
{
   long double c=42;

   c/3;

   printf("c=%Lf\n",c);

   return 0;
}

Answer 2

Yes -- for long double, you need to use %Lf (i.e., upper-case 'L').