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Identifiers in c programming with Example
An identifier in C programming is the name given to a variable, function, or other user-defined entity. It basically consists of a string of characters that adhere to specific naming convention rules and criteria. Different software elements are given distinctive names using identifiers so that programmers may refer to them and change their values or behavior.
In order to uniquely identify an entity during program execution, the identifier is a user-defined name for that entity.
The following are some crucial ideas to comprehend regarding identifiers in C programming:
Naming Rules: Identifiers in C must adhere to certain rules:
An identifier must begin with a letter (a-z, A-Z) or an underscore (_).
An identification may have letters, numbers (0–9), or underscores after the first character.
The case of an identifier affects how it is used, therefore "count" and "Count" are processed differently.
An identifier may only be a maximum of 31 characters long.
Examples of Valid Identifiers: Here are some illustrations of appropriate C programming identifiers:
- variable
- sum
- _count
- MAX_SIZE
- calculate Area
Reserved Words: Because they have specific linguistic connotations, reserved words, usually referred to as keywords, are not allowed to be used as identifiers in C programming. In the C programming language, reserved terms include "int," "if," "while," and "for."
Good Naming Practices: To improve code readability and maintainability, identifiers should have names that are meaningful and descriptive. The code may be simpler to understand if variables and functions have names that appropriately describe their functions or contents.
Identifier Scope: Where in a program an identifier can be accessed depends on its scope. The local scope of variables and functions declared inside a block (such as a function or a set of curly braces) restricts their accessibility to that block. The program can access variables declared outside of any block since they have a global scope.
Good Naming Practices: To improve code readability and maintainability, identifiers should have names that are meaningful and descriptive. The code may be simpler to understand if variables and functions have names that appropriately describe their functions or contents.
Identifier Scope: Where in a program an identifier can be accessed depends on its scope. The local scope of variables and functions declared inside a block (such as a function or a set of curly braces) restricts their accessibility to that block. The program can access variables declared outside of any block since they have a global scope.
In short, identifiers are names that are assigned to variables, functions, and other program objects in C programming. They adhere to a set of naming conventions, and selecting appropriate identifiers is crucial for developing comprehensible code.
Scope of an identifier
The area of the program where an identifier is visible or accessible is referred to as its scope. There are primarily three scopes for identifiers in C programming:
Global Scope:
- The scope of any identifiers declared outside of a function or block is global.
- Anywhere in the program, including other functions and blocks, can access global identifiers.
- The values of global variables are maintained over the course of the program.
- Any section of the program can call global functions.
Example:
#include <stdio.h>
int globalVariable = 10;
void globalFunction() {
printf("This is a global function.\n");
}
int main() {
printf("The value of globalVariable is %d\n", globalVariable);
globalFunction();
return 0;
}
Local Scope:
- The local scope applies to identifiers declared inside a block, such as a function or a loop.
- Local identifiers can only be used in the block in which they are declared.
- In a given function or block, local variables are often used for temporary storage.
- Only calls from within the same block are permitted for local functions.
Example:
#include <stdio.h>
void localFunction() {
int localVar = 20;
printf("This is a local function. The value of localVar is %d\n", localVar);
}
int main() {
int mainVar = 30;
printf("This is the main function. The value of mainVar is %d\n", mainVar);
localFunction();
return 0;
}
Function Prototype Scope:
- The scope of any identifiers declared in a function prototype is only that prototype.
- Before a function is defined, its signature is declared using function prototypes.
- A function prototype is the sole place where the identifiers are accessible.
Example:
#include <stdio.h>
void prototypeFunction(int param); // Function prototype
int main() {
prototypeFunction(50);
return 0;
}
void prototypeFunction(int param) { // Function definition
printf("This is the prototype function. The value of the parameter is %d\n", param);
}
Rules for Creating Identifiers
- Only numbers, underscore symbols, and letters—both uppercase and lowercase—can be used as identifiers.
- A numerical value shouldn't be the first part of an identification. The first character can be a letter or an underscore.
- No special characters, not even white space, shall be used between the identifiers. Only the underscore symbol is permitted, though.
- It is not recommended to use keywords as identifiers.
- The length of an identifier is unrestricted. The compiler, however, only takes into account the first 31 characters.
- In its application, an identifier must be distinct.
- Every identifier has a lowercase letter at the beginning.
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