Wrong output when printing long double with printf in mingw

Asked Sep 02 '21 at 09:52

Active Sep 02 '21 at 11:11

Viewed 187 times

I was trying to use long doubles in a bigger code but even this doesn't seem to work.

#include <stdio.h>
#include <math.h>

int main(){
    
    long double I = 10.0;
    long double YOU = 2.0;
    long double WE = I/YOU;
    printf("%Lf", I);


    return 0;
}

No errors, but the output is

-0.000000

edited Sep 02 '21 at 11:11

recolic

asked Sep 02 '21 at 09:52

XxCharbonChainsxX

2

I can not reproduce your issue in `linux-gcc 11.1.0`. The output is 10.000000 on my side. – recolic Sep 02 '21 at 09:54
What compiler are you using? What version of it? On what system? – Some programmer dude Sep 02 '21 at 09:55
I installed minGW installation manager – XxCharbonChainsxX Sep 02 '21 at 09:56
if that's the answer..? – XxCharbonChainsxX Sep 02 '21 at 09:56
There is nothing wrong with the code itself (except that you print the wrong value). – Weather Vane Sep 02 '21 at 09:58
4

MinGW uses the Microsoft runtime, and there is said to be some problem. What happens if you try to replace `printf()` by `__mingw_printf()`? – the busybee Sep 02 '21 at 09:59
3

MS doesn't support `long double` but implements it as `double`. – Weather Vane Sep 02 '21 at 10:01
3

Might need `#define __USE_MINGW_ANSI_STDIO 1` as the very first line. – Shawn Sep 02 '21 at 10:02
which compiler do you recommend me so I solve the issue definitely? – XxCharbonChainsxX Sep 02 '21 at 10:03
do you know perhaps if there is also a 'scanf()' with the same prefix __mingw_ ? @thebusybee – XxCharbonChainsxX Sep 02 '21 at 10:11
Are you sure you actually *need* the extra range and precision of `long double`? Typically, you should use `double` unless there is a good reason not to, because that is the default type for literal floating point values and for arguments to variadic functions. – Weather Vane Sep 02 '21 at 10:19
yes, I am doing a math project @WeatherVane – XxCharbonChainsxX Sep 02 '21 at 10:25
I think the MinGW-w64 compilers installed by MSYS2 default to using their own formatted I/O functions (for `printf` etc.) in place of the ones from MSVCRT.DLL. – Ian Abbott Sep 02 '21 at 13:44

Wrong output when printing long double with printf in mingw

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