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[Bug c/46908] New: printf not handling printing of double correctly in certain cases
- From: "adrian.hawryluk at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Sun, 12 Dec 2010 16:12:23 +0000
- Subject: [Bug c/46908] New: printf not handling printing of double correctly in certain cases
- Auto-submitted: auto-generated
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46908
Summary: printf not handling printing of double correctly in
certain cases
Product: gcc
Version: 4.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: adrian.hawryluk@gmail.com
Host: Windows XP SP2
Target: mingw32
Build: 4.5.0
This is a weird one. Under different compile options, it does it wrong in
different ways. :)
#include <stdio.h>
#include <math.h>
void printld(long double* pld)
{
int i;
printf("*%p = ", pld);
for (i = 0; i < sizeof(long double); ++i) {
printf("%02x ", ((unsigned char*)pld)[i]);
}
printf("\n");
}
int main()
{
long double number1 = 1.0;
long double number2 = 1.0;
printf ("%lf, %lf\n", number1, number2);
printf ("Enter number1: ");
scanf ("%lf", &number1);
printf ("Enter number2: ");
scanf ("%lf", &number2);
printf ("%lf, %lf\n", number1, number2);
printf ("%lf, %lf\n", number1, number1);
printld(&number1);
printld(&number2);
return 0;
}
C:\tmp>gcc -o tmp.exe file.c
C:\tmp>tmp
0.000000, 0.000000
Enter number1: 3
Enter number2: 4
3.000000, 0.000000
3.000000, 0.000000
*0022FF30 = 00 00 00 00 00 00 08 40 ff 3f 00 00
*0022FF20 = 00 00 00 00 00 00 10 40 ff 3f 00 00
C:\tmp>gcc -std=c99 -o tmp.exe file.c
C:\tmp>tmp
1.000000, 1.000000
Enter number1: 3
Enter number2: 4
0.000000, 0.000000
0.000000, 0.000000
*0022ff30 = 00 00 00 00 00 00 08 40 ff 3f 00 00
*0022ff20 = 00 00 00 00 00 00 10 40 ff 3f 00 00
There was even a way of printing the same variable (number1) twice on a line
and it would output it twice. That is why I had put in:
printf ("%lf, %lf\n", number1, number1);
as a test, but it didn't show up in this test code.
C:\tmp>gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=c:/mingw/bin/../libexec/gcc/mingw32/4.5.0/lto-wrapper.exe
Target: mingw32
Configured with: ../gcc-4.5.0/configure
--enable-languages=c,c++,ada,fortran,objc,obj-c++ --disable-sjlj-exceptions
--with-dwarf2 --enable-shared --enable-libgomp --disable-win32-registry
--enable-libstdcxx-debug --enable-version-specific-runtime-libs
--disable-werror --build=mingw32 --prefix=/mingw
Thread model: win32
gcc version 4.5.0 (GCC)
--
A