Is there any way to make sure the floating point arithmetic result the same in both linux and windows -

my programe runs both in linux , windows, have make sure floating point arithmetic same result in different os.

here code:

for (int = 0; < 100000; ++i) {     float d_value = 10.0f / float(i);     float p_value = 0.01f * float(i) + 100.0f; } 

i use "g++ -m32 -c -static -g -o0 -ffloat-store" build code in linux. use "/fp:precise /o2" build code in windows vs2005.

when printf "d_value" , "p_value", "d_value" same both in linux , windows. "p_value" different sometimes. exsample, print "p_value" hexadecimal format:

windows:  42d5d1eb linux:    42d5d1ec 

why dose happen?

my g++ version is

configured with: ../src/configure -v --with-pkgversion='debian 4.4.5-8' --with-bugurl=file:///usr/share/doc/gcc-4.4/readme.bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.4 --enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.4 --libdir=/usr/lib --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --enable-targets=all --with-arch-32=i586 --with-tune=generic --enable-checking=release --build=i486-linux-gnu --host=i486-linux-gnu --target=i486-linux-gnu thread model: posix gcc version 4.4.5 (debian 4.4.5-8) 

i use flag -ffloat-store, because of someone's suggestion here: different math rounding behaviour between linux, mac os x , windows

use /fp:strict on windows tell compiler produce code strictly follows ieee 754, , gcc -msse2 -mfpmath=sse on linux obtain same behavior there.

the reasons differences seeing have been discussed in spots on stackoverflow, best survey david monniaux's article.

---

the assembly instructions obtain when compiling gcc -msse2 -mpfmath=sse follow. instructions cvtsi2ssq, divss, mulss, addss correct instructions use, , result in program p_value contains @ 1 point 42d5d1ec.

    .globl  _main     .align  4, 0x90 _main:                                  ## @main     .cfi_startproc ## bb#0:     pushq   %rbp ltmp2:     .cfi_def_cfa_offset 16 ltmp3:     .cfi_offset %rbp, -16     movq    %rsp, %rbp ltmp4:     .cfi_def_cfa_register %rbp     subq    $32, %rsp     movl    $0, -4(%rbp)     movl    $0, -8(%rbp) lbb0_1:                                 ## =>this inner loop header: depth=1     cmpl    $100000, -8(%rbp)       ## imm = 0x186a0     jge lbb0_4 ## bb#2:                                ##   in loop: header=bb0_1 depth=1     movq    _p_value@gotpcrel(%rip), %rax     movabsq $100, %rcx     cvtsi2ssq   %rcx, %xmm0     movss   lcpi0_0(%rip), %xmm1     movabsq $10, %rcx     cvtsi2ssq   %rcx, %xmm2     cvtsi2ss    -8(%rbp), %xmm3     divss   %xmm3, %xmm2     movss   %xmm2, -12(%rbp)     cvtsi2ss    -8(%rbp), %xmm2     mulss   %xmm2, %xmm1     addss   %xmm0, %xmm1     movss   %xmm1, (%rax)     movl    (%rax), %edx     movl    %edx, -16(%rbp)     leaq    l_.str(%rip), %rdi     movl    -16(%rbp), %esi     movb    $0, %al     callq   _printf     movl    %eax, -20(%rbp)         ## 4-byte spill ## bb#3:                                ##   in loop: header=bb0_1 depth=1     movl    -8(%rbp), %eax     addl    $1, %eax     movl    %eax, -8(%rbp)     jmp lbb0_1 lbb0_4:     movl    -4(%rbp), %eax     addq    $32, %rsp     popq    %rbp     ret