Error in My Code: Undefined Symbols for x86_64

[Amany Gouda]

I have received this error :

Undefined symbols for architecture x86_64:
"start", referenced from:

-u command line option

(maybe you meant: __gfortrani_library_start)

ld: symbol(s) not found for architecture x86_64

collect2: error: ld returned 1 exit status

what is this mean??

the code is :

program   exercise2

  integer:: i,j
  real,dimension (5,5)::A

  open(20,file='A.txt',status='old')  do i=1,5
  read(*,*)(a(i,j),j=1,5)
  end do

  do i=1,5
  write(20,*)(a(i,j),j=1,5)
  end do

close(20)

  end program exercise2

 

[jedishrfu]

WHat command are you using to run the code?

 

[Amany Gouda]

WHat command are you using to run the code?

I am using gfortran in macbook air version 10.9.5

 

[DrClaude]

I am using gfortran in macbook air version 10.9.5

Could you show exactly the compiling command? The problem might be with your installation of gcc.

 

[Amany Gouda]

compiling command

sigmat-no-air:desktop amany$gfortran exercise2.f90

 

[DrClaude]

Then gfortran is not installed properly.