c - scanf GCC for long double -

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• scanf not taking in long double 5 answers

i'm using gcc 4.8.1 std=c99 on windows 7. what's correct place holder long double when using scanf , fscanf? tried %lf , %lf , neither working. compile command gcc -std=c99 main.c -o main.exe. when omit std=c99 works fine.

#include <stdlib.h> #include <stdio.h> int main() {     long double x = 0;     scanf("%lf", &x);      printf("x = %lf\n", x);      return 0;  } 

it works fine me, on centos 6.6, or without -std=c99:

$ gcc --version gcc (gcc) 4.4.7 20120313 (red hat 4.4.7-11) copyright (c) 2010 free software foundation, inc.  $ gcc x.c -o x -std=c99 -wall -pedantic $ ./x 123.456 x = 123.456000  $ gcc x.c -o x  -wall -pedantic $ ./x 123.456 x = 123.456000 

i'm assuming you're on linux (or mac osx), , assume you're using libc matches installed gcc.

however

there issues if you're using gcc mingw on windows:

scanf not taking in long double

dev-c++ uses mingw, uses gcc compiler , microsoft runtime library. unfortunately, components disagree on underlying type used long double (64 vs. 80 or 96 bits, think). windows assumes long double same size double; gcc makes long double bigger.

either choice valid, combination results in broken c , c++ implementation.