Global variables in C
In programming, variables are the fundamental units for storing and manipulating data. For generating adaptive and accessible code in the popular programming language C, global variables are crucial. The concept of global variables will be discussed in this article, its significance and its advantages. Using global variables in the C program will be fine for you.
What are Global variables?
In contrast to local variables, which are restricted to particular functions or code blocks, global variables can be accessed and modified by any function within the program, making them accessible throughout the entire codebase and offering a convenient method of sharing data between various functions.
Source code for the global variables:
#include<stdio.h>
int x = 0;
void meth1(void);
void meth2(void);
int main()
{
printf(“Starting value of global variables : %d\n”, x);
meth1();
meth2();
printf(“Last value of global variables: %d\n”, x);
return 0;
}
void meth1(void) {
x = 10;
printf(“Inside meth1: global variables %d\n”, x);
}
void meth2(void) {
x += 5;
printf(“inside meth2: global variables %d\n”, x);
}
Output:
![Global variables in C](https://static.tutorialandexample.com/c/global-variables-in-c1.png)
Explanation:
- The program creates the global variable 'x' with a starting value of 0.
- The 'main' Function starts by printing the starting values of the global variable, which is 0.
- It calls the 'meth1' function, which assigns the value 10 to the global variable x and prints its value.
- After returning from the 'meth1', the main Function calls the meth2 Function, which increments the global variable x by 5 and prints its value.
- Finally, the 'main' Function prints the last value of the global variable, which is 15.
Example 2:
#include<stdio.h> // Constants from the Reference class const double ROOT2 = 1.41; const double PI = 3.14; const double MAX_LENGTH = 12; //Function to calculate the area of a circle double area(double radius) { double circle_area = PI * radius * radius; return circle_area; } int main() { double radius = 23; printf("The area of a circle with a radius of %.2f is %.2f\n", radius, area(radius)); return 0; } Output:
![Global variables in C](https://static.tutorialandexample.com/c/global-variables-in-c2.png)
- Three global variables ('ROOT2', 'PI', and 'MAX_LENGTH') are declared in the C code to represent the constants from the 'Reference' in C. The 'const' keyword is used to specify these variables as constants outside of any functions.
- The area of a circle may be determined using the 'area()' Function. The radius is a parameter, and the computation uses the 'PI' constant.
- We define the variable radius and give it the value 23 in the "main()" Function. Then, using the 'area()' Function, we use 'printf()' to display the circle's determined area.
Advantages of Global Variables
1. Accessibility and Data Sharing
Data exchange between functions is made simple via global variables. They eliminate the need to pass values through function arguments because they are available from wherever in the program, simplifying the code and making it easier to read.
2. Code reusability and Modularity
The modular architecture of your code may be achieved by employing global variables. Global variables can hold information that has to be shared across different functions or modules, fostering code reuse and minimizing duplication.
3. Constants and Configurations
Constants or configuration settings that don't change throughout the program's execution can be stored in global variables. This makes maintenance and changes easier by enabling centralized control over crucial values.
4. Convenience in Small programs
Global variables can streamline the organization of the code and minimize the need for unnecessary parameter passing in small programs where complexity and scalability are not key problems.
Best Practices for Using Global Variables
1. Document Global Variables
To ensure that other developers understand global variables' behavior and prevent accidental changes, it is important to thoroughly describe their use, intended purpose, and any side consequences.
2. Declare Global Variables as Static
To restrict the scope of global variables to the file in which they are defined, declare them as static. Encapsulation is encouraged, and the possibility of name conflicts with other files is decreased.
3. Limit their Usage
Global variables should only be used in circumstances when they clearly have an advantage. When local variables or function parameters will do, avoid using global variables.
Conclusion
In some programming settings, global variables in C offer simplicity and flexibility by allowing data to be shared between functions and modules. Its use should be carefully evaluated to avoid possible hazards such as accidental alterations, inadequate encapsulation, and thread safety issues. Make use of global variables' advantages while preserving the readability and Modularity of your code by adhering to standard practices and using them sparingly. To build dependable and maintainable C programs, it is crucial to comprehend the subtleties of global variables. Remember, using them effectively requires balancing convenience and potential downsides.