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[anand3162]

Here is a question regarding a Fortran compile error.

I have a program with a nested if statement as follows,

If (conditionA) then
If (conditionB) then
Executable lines of code
Executable lines of code
Executable lines of code
Endif
Endif

When I do a fast compile of the above section of code, I have no problems and the code executes smoothly. However, when I run the code within the debugger, then the program crashes at conditionA for an array indexing of bounds issue.

My question is why does the fast compile not crash? Why is it that only the debug compile crashes? If the array indexing is out of bounds for the debug compile, it will be out of bounds for fast compile also.

[mecej4]

[anand3162]

For instance a sample code could be

do k = 1, numberofinputs
If (inputisnumber) then
numindex = numindex+1
Input(numindex) = Numvalue
endif
enddo

if (Input(numindex) .eq. 1) then
executable lines
executable lines
endif

----
numindex is declared as an integer.

Input is a 1 dimensional array of length 50, goes from Input (1) to Input (50).

If inputisnumber is false, numindex remains 0 throughout.

Therefore, Input(0) returns array index out of bounds

This index out of bounds happens only under debug compile. Why is it so?

[davidb]

[anand3162]

David,

I do not think it is zero. I can see it is zero, when I look at the program in the debugger.

numindex is declared but not assigned a value. It stays at its default value of 0. But the array that uses numindex as its index will then be Input(0) but Input exists from 1-50 only.

Are you suggesting that this is a programming error?

I still do not understand why debug compile shows this as a bug and the optimized compile does not. For something as straightforward as an array index why does optimized compile miss it?

Is there something I can do so that such errors will be trapped out even with optimized compile?

[DanRRight]

Zeroise/initialuse all manually. The default initial state formally is not a zero but any trash in memory could be in given location. Compiler usually takes care and zeroises arrays and variables for you (not always) but when in debug mode it is not making you excuses looking at all possible faults of programmer. I use compile option /zeroise

[mecej4]

[JohnCampbell]

If numindex = 0 is a valid outcome from the do loop then you should change the second part of your code to cope with that:

You should also initialise numindex = 0 before the start of the code group
and also change the first part to check numindex keeps in range.
Grouping these suggested changes would have:

[davidb]

[anand3162]

Thanks you David, John, mecej4, and Dan.

All your inputs have helped me clarify this issue of mine. I really appreciate your time.