Global Variables and Scope In C Language

In C, the scope of a variable refers to the portion of the program where the variable can be accessed. Variables can have either global or local scope.

1. Global variables: Global variables are declared outside of any function and are accessible from anywhere in the program. They are also known as external variables. They are defined outside of any function, usually at the beginning of the source file.

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int global_variable = 10; int main() {    // global_variable can be accessed here }

1. Local Variables: Local variables are declared within a function and are only accessible within that function. They are also known as automatic or automatic storage variables. They are defined inside a function, usually at the beginning of the function.

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int main() {    int local_variable = 10;    // local_variable can be accessed only inside this function }

It's important to note that global variables retain their values between function calls, whereas local variables are created and destroyed each time the function is called. Also, it's good practice to use global variables only when they are necessary, because they can be accessed and modified by any function in the program, which can lead to unexpected behavior and bugs.

Additionally, it's important to keep in mind that global variables are also accessible to other source files if the global variable is declared with the keyword "extern" in the other source files. It's a way to share variables across multiple source files.