A variable is a name of memory location. It is used to store data. Its value can be changed and it can be reused many times.
There are many types of variables in c:
A variable that is declared inside the function or block is called local variable.
You must have to initialize the local variable before it is used.
A variable that is declared outside the function or block is called global variable. Any function can change the value of the global variable. It is available to all the functions.
A variable that is declared with static keyword is called static variable.
If you call this function many times, local variable will print the same value for each function call e.g, 11,11,11 and so on. But static variable will print the incremented value in each function call e.g. 11, 12, 13 and so on.
All variables in C that is declared inside the block, are automatic variables by default. By we can explicitly declare automatic variable using auto keyword.
We can share a variable in multiple C source files by using external variable. To declare a external variable, you need to use extern keyword.