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Despite running gfortran in a 64-bit machine, I get a 32-bit integer overflow problem. Could you please help me figure out what the problem is?

A minimal (non) working example is:

PROGRAM TestInteger
    INTEGER:: mult
        mult = 1024*1024*1024
        PRINT *,mult
        mult = mult*2
        PRINT *,mult
        mult = mult*2
        PRINT *,mult
    END PROGRAM

gfortran version:

$ gfortran -v
Using built-in specs.
COLLECT_GCC=gfortran
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/4.8/lto-wrapper
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.8.4-2ubuntu1~14.04' --with-bugurl=file:///usr/share/doc/gcc-4.8/README.Bugs --enable-languages=c,c++,java,go,d,fortran,objc,obj-c++ --prefix=/usr --program-suffix=-4.8 --enable-shared --enable-linker-build-id --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --with-gxx-include-dir=/usr/include/c++/4.8 --libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --enable-gnu-unique-object --disable-libmudflap --enable-plugin --with-system-zlib --disable-browser-plugin --enable-java-awt=gtk --enable-gtk-cairo --with-java-home=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64/jre --enable-java-home --with-jvm-root-dir=/usr/lib/jvm/java-1.5.0-gcj-4.8-amd64 --with-jvm-jar-dir=/usr/lib/jvm-exports/java-1.5.0-gcj-4.8-amd64 --with-arch-directory=amd64 --with-ecj-jar=/usr/share/java/eclipse-ecj.jar --enable-objc-gc --enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --with-tune=generic --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.8.4 (Ubuntu 4.8.4-2ubuntu1~14.04)

Computer architecture:

$ uname -m
x86_64

Test:

$ gfortran -o testInteger TestInteger.f90 
$ file testInteger 
testInteger: ELF 64-bit LSB  executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.24, BuildID[sha1]=504c86d2d4a695714627724e99ef68f3c5fc76ea, not stripped
$ ./testInteger 
 1073741824
-2147483648
          0

With the -m64 flag, the behaviour is still the same.

toliveira
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    http://stackoverflow.com/questions/9569756/fortran-the-largest-and-the-smallest-integer – stark Nov 27 '15 at 15:25
  • Not really duplicate, but from the answer to the other question I learnt that I should use INTEGER*8 instead of INTEGER, which is 32 bits no matter the platform or compilation flag. – toliveira Nov 30 '15 at 20:40
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    Since you use gfortran, you can use compiler options : `-fdefault-integer-8` (https://gcc.gnu.org/onlinedocs/gfortran/Fortran-Dialect-Options.html#Fortran-Dialect-Options) it will promote `integer` to be 64bits `integer`. – Pascal H. Mar 20 '20 at 18:04

0 Answers0