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I do not understand why this code does not produce any segmentation fault. I was expecting some errors while compiling the code or in run-time, but it runs apparently correctly.

program alloc

implicit none

real, dimension(:,:), allocatable :: myVec

allocate(myVec(3,2))    

myVec=1.

myVec(100,3)=10.

write(*,*) myVec(1,1)

return
end

Could somebody shed some light on this behaviour?

Vladimir F Героям слава
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alie
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1 Answers1

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With gfortran, you can use the -fbounds-check compiler flag (or -C with ifort) in order to look for this kind of errors. When you compile your example with this option, the program produces:

Fortran runtime error: Index '3' of dimension 2 of array 'myvec' above upper bound of 2

As to why the program does not crash immediately, this question contains more details.

ewcz
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