Redeclaration of global variable vs local variable

by

In C, the statement int a; when made at file scope, is a declaration and a tentative definition. You can have as many tentative definitions as you want, as long as they all match each other.

If a definition (with an initializer) appears before the end of the translation unit, the variable will be initialized to that value. Having multiple initialization values is a compiler error.

If the end of the translation unit is reached, and no non-tentative definition was found, the variable will be zero initialized.

The above does not apply for local variables. Here a declaration also serves as a definition, and having more than one leads to an error.

More Related Contents:

  1. What is the difference between a definition and a declaration?
  2. Why can I define a variable twice in C?
  3. Can I change the datatype of previously declared variable in C?
  4. What happens to a declared, uninitialized variable in C? Does it have a value?
  5. Why is volatile needed in C?
  6. Variable declaration placement in C
  7. Defining static const integer members in class definition
  8. How do I understand complicated function declarations?
  9. Where you can and cannot declare new variables in C?
  10. Why is #include not required to use printf()?
  11. The spiral rule about declarations — when is it in error?
  12. What is this strange function definition syntax in C? [duplicate]
  13. Variable definition inside switch statement
  14. Complex declarations
  15. can size of array be determined at run time in c?
  16. C multiple single line declarations
  17. forward declaration of a struct in C?
  18. Assign multiple values to array in C
  19. Can a union be initialized in the declaration?
  20. Is is a good practice to put the definition of C++ classes into the header file?
  21. Difference between pointer to pointer and pointer to array?
  22. C the same global variable defined in different files
  23. Making an array using pointers in c
  24. How to truncate a file in C?
  25. Why do arrays in C decay to pointers?
  26. What does the brk() system call do?
  27. Variadic macro trick
  28. Is NULL in C required/defined to be zero?
  29. Is typecast required in malloc? [duplicate]
  30. problems with char array = char array

Leave a Comment