Scope error

[avi05]

void func1(void)
{

strans obj;\\\\struct
unsigned int i,ix;
ix=1;

if (a>0)\\\\\\\\\\\\\a is global int
ix=a;

for (i=ix;i<5;i++)
{
func2(i,obj);
\\\\\\\\\\\\\\\\\\\\\\i value here i =1 ok
func3(obj);
\\\\\\\\\\\\\\\\\\\\\\ func3 ok
\\\\\\\\\\\\\but after this func3 call i value===0\\\\\error
\\not making any change to or passing address of i in func3 but still getting \\reset
\\if i use static for i variable it works correctly
\\but scope of i even though local is through out function1 is it not?
\\please tell me why this problem occurs..


}

}

could it be a stack problem were i is lost when func3 is called ,,isnt static used the other way around to retain i value when flow exits out of func1..thankyou for all posts

[Banfa]

You probably have a problem in func3, some sort of out of bounds write to a local array variable in func3 could corrupt the local data in func1.

[avi05]

thankyou bafta i am using a gnu cross compiler when i got this error ,but when the same code is ported to borland bc5 it works correctly...could it be compiler optimisation in bc5 that is avoiding this out of bounds write into array...

[newb16]

It may be anything - endianness, word/dword alignment, difference in size of int/long types. Try to pad i,ix declaration with some local arrays filled with some like 0xcc and see then what happens to them and how much of them is zeroed.

[Banfa]

@avi05
If you are writing outside of an array bounds then you have invoked undefined behaviour.

Anything can happen with undefined behaviour including the program appearing to work and it is likely that different things would happen on different platforms so just because your code appears to work in Borland BC5 doesn't mean that there is no error in the code. It just means BC5 is reacting to undfined behaviour in a different way to the gnu cross compiler.

You need to check the code of func3 and see if you can see the error.