A C variable is a named storage location in memory that holds a value of a specific data type (such as integer, float, or character). You can use variables to store and manipulate data in your C programs.
About C Variable
Declaration: A variable in C must be declared before it is used. The declaration includes the variable’s name and its data type.
int age
Initialization: A variable can be initialized with a value when it is declared, or its value can be set later in the program.
int age = 35;
Example:
#include <stdio.h>
int main() {
int age = 35;
printf("John age is %d", age);
return 0; // Exit the program successfully
}
Note: %d is used to print integers value.
Output:
Scope of Variable
A variable’s scope refers to where it can be accessed. A variable can be local (inside a function) or global (outside any function).
Local Variables: These are variables declared inside a function or block. Their scope is limited to that function or block.
Global Variables: These are variables declared outside of any function. They can be accessed by any function in the program.
Example:
#include <stdio.h>
int globalVar = 45;
int main() {
int localVar = 35;
printf("local variable %d\n", localVar);
printf("global variable %d", globalVar);
return 0; // Exit the program successfully
}
Output:
global variable 45
Variable Naming Rules
A variable name in C must start with a letter or an underscore and can be followed by letters, digits, or underscores. It is case-sensitive, so age and Age would be different variables.