Can a const variable be extern?
Yes, you can use them together.
What is the difference between extern and global variable?
Global variable is a variable that is available throughout the program. An extern variable is also available throughout the program but extern only declares the variable but it doesn’t allocate any memory for this variable. It means you can’t ise the variable till you define it.
Can we initialize extern variable in C?
Here are some important points about extern keyword in C language, External variables can be declared number of times but defined only once. Variables with “extern” keyword are only declared not defined. Initialization of extern variable is considered as the definition of the extern variable.
What is extern used for?
the extern keyword is used to extend the visibility of variables/functions. Since functions are visible throughout the program by default, the use of extern is not needed in function declarations or definitions. Its use is implicit. When extern is used with a variable, it’s only declared, not defined.
What is the purpose of extern variable?
Can we use extern inside a function?
An external variable may also be declared inside a function. In this case the extern keyword must be used, otherwise the compiler will consider it a definition of a local (automatic) variable, which has a different scope, lifetime and initial value.
Why do we use extern in C?
Why do we need extern C?
Using extern “C” lets the compiler know that we want to use C naming and calling conventions. This causes the compiler to sort of entering C mode inside our C++ code. This is needed because C++ compilers mangle the names in their symbol table differently than C compilers and hence behave differently than C compilers.
Is extern necessary?
If the declaration describes a function or appears outside a function and describes an object with external linkage, the keyword extern is optional. If you do not specify a storage class specifier, the function is assumed to have external linkage.