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Is there any way to know / warn if a global variable is uninitialized with gcc ?
I got it for local/ atomic variables “-Wuninitialized”
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In computing, an uninitialized variable is a variable that is declared but is not set to a definite known value before it is used. It will have some value, but not a predictable one. As such, it is a programming error and a common source of bugs in software.
Global variables get there space in the data segment which is zeroed out. It is not compiler specific but defined in the C standard. So it will always print 0.
Default value→ All uninitialized global variables will have 0 as the default value.
A data segment is a portion of the virtual address space of a program, which contains the global variables and static variables that are initialized by the programmer.
No!
Global and static variables are initialized implicitly if your code doesn't do it explicitly as mandated by the C standard.
In short, global and static variables are never left uninitialized.
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6.9.2 External object definitions
Semantics
1 If the declaration of an identifier for an object has file scope and an initializer, the declaration is an external definition for the identifier.
2 A declaration of an identifier for an object that has file scope without an initializer, and without a storage-class specifier or with the storage-class specifier static, constitutes a tentative definition. If a translation unit contains one or more tentative definitions for an identifier, and the translation unit contains no external definition for that identifier, then the behavior is exactly as if the translation unit contains a file scope declaration of that identifier, with the composite type as of the end of the translation unit, with an initializer equal to 0.
The above two clauses (from the standard) guarantee that file-scope (global) objects are always initialized.
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