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Difference between local and global variable/definitions

The main difference between a local and a global variable is that a local variable is declared inside a function, and a global variable is declared outside a function in a program.

A variable is a name assigned to a memory location. It can be used to manipulate the values ​​stored in this memory location throughout the entire program. There are two types of variables in programming languages ​​such as C. They are local variables and global variables. A local variable is declared in a function and is only available to that function. On the other hand, a global variable is declared outside of a function in a program. This is available to any statement in the entire program.

What is a Local Variable

A function or method is a set of instructions that perform a specific task. A local variable is a variable declared inside a function. It is only available inside that specific function. Other functions in the same program cannot access this variable. Evaluating a local variable from some other function will give an error. Difference between local and global variable

Program execution starts from the main method. When the main method calls a function, control is transferred to that function from the main method. The local variable exists until the function is executed. When this function completes, control is passed back to the main method. Therefore, the local variable only exists until the function is executed. When the function finishes executing, the local variable is destroyed.

In the above program, the values ​​”a” and “b” are passed to the calc_area function. Inside this function, a new variable named area is created. This variable is a local variable. It is only available inside this function. It cannot be accessed inside the main method.

What is a Global Variable

A global variable is a variable that is declared outside of all functions within a program. There can be several functions in one program. All of these functions can access these global variables. Therefore, the global variable is not very safe as the value can be changed by other functions. The global variable exists until the completion of the entire program. Difference between local and global variable

Global variables are useful when multiple functions operate on the same data. On the other hand, the value of a global variable is unreliable because it can be changed.

In the above program, “a” and “b” are global variables. Therefore, these variables are available in the sum and increment_values ​​functions. The sum function prints the sum of a and b. The increment_values ​​function increments the values ​​”a” and “b” by 1. Printing the values ​​”a” and “b” in the main method will print the incremented values. Therefore, global variables are available to all functions in the program.

Difference between local and global variable

Definition

A local variable is a variable that is declared inside a function of a computer program. A global variable is a variable that is declared outside the functions of a computer program. This is the main difference between a local and a global variable.

Associability

In addition, although the local variable is only accessible within the declared function, the global variable is accessible to all functions in the program.

Existence

Another important difference between a local and a global variable is their existence. The local variable exists until the function is executed. The local variable is created when the function starts executing and destroyed when the function ends. On the other hand, a global variable exists for the entire duration of the program execution.

reliability

In addition, the local variable is more reliable and secure because the value cannot be changed by other functions. In contrast, a global variable is available to several functions. Therefore, its meaning can be changed.

Conclusion

Programming languages ​​like C have two types of variables: local and global variables. The difference between a local and a global variable is that a local variable is declared inside a function, and a global variable is declared outside a function in a program.

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