Keywords and identifiers are fundamental concepts in the C programming language. Understanding these concepts is crucial for writing correct and effective C programs. In this tutorial, we will explore keywords and identifiers in C, their significance, and how to use them properly. Whether you are a beginner or an experienced programmer, this guide will provide you with a comprehensive understanding of keywords and identifiers in C.
Let’s dive into the world of C programming and explore keywords and identifiers in detail.
Introduction to Keywords
Keywords, also known as reserved words, are pre-defined words in the C programming language that have specific meanings and functionalities. These words are reserved for the compiler and cannot be used as identifiers (variable names, function names, etc.) in your C programs.
Keywords are an essential part of the C language syntax and form the building blocks of C programs. They provide a set of instructions to the compiler to perform specific tasks or operations. Examples of keywords in C include
float, and many more.
Complete List of C Keywords
Here is a complete list of keywords in the C programming language:
|auto||Defines an automatic variable|
|break||Terminates the current loop or switch statement|
|case||Defines a case statement within a switch statement|
|char||Declares a character type|
|const||Declares a read-only variable|
|continue||Skips the current iteration of a loop|
|default||Specifies the default case in a switch statement|
|do||Starts a do-while loop|
|double||Declares a double-precision floating-point type|
|else||Defines an alternative branch in an if statement|
|enum||Declares an enumeration type|
|extern||Declares a variable or function as external|
|float||Declares a floating-point type|
|for||Begins a for loop|
|goto||Transfers control to a labeled statement|
|if||Starts an if statement|
|inline||Suggests the compiler to perform inline expansion|
|int||Declares an integer type|
|long||Declares a long integer type|
|register||Suggests the compiler to store the variable in a register|
|return||Exits the current function and returns a value|
|short||Declares a short integer type|
|signed||Declares a signed integer type|
|sizeof||Returns the size of a type or variable in bytes|
|static||Declares a static variable or function|
|struct||Defines a structure|
|switch||Starts a switch statement|
|typedef||Creates a new data type using an existing type|
|union||Defines a union|
|unsigned||Declares an unsigned integer type|
|void||Specifies an empty type or no value|
|volatile||Declares a volatile variable|
|while||Begins a while loop|
It’s important to note that the above keywords are case-sensitive in C. Therefore, you must use them exactly as shown in the list.
Identifiers are user-defined names used to identify various entities in a C program, such as variables, functions, arrays, and labels. In simpler terms, identifiers are like labels that represent specific memory locations where data is stored or instructions are executed.
Unlike keywords, identifiers are not reserved words and can be chosen freely by the programmer. However, there are certain rules and best practices to follow when creating identifiers to ensure readability, maintainability, and avoid conflicts.
Rules for Creating Identifiers
Here are the rules for creating valid identifiers in C:
- An identifier can consist of letters (both uppercase and lowercase), digits, and underscores (
_), but it must begin with a letter or an underscore.
- C is case-sensitive, so uppercase and lowercase letters are considered different. For example,
myvariableare distinct identifiers.
- The length of an identifier can be up to 31 characters.
- You cannot use C keywords as identifiers.
- Identifiers cannot contain special characters such as
- The use of reserved library function names as identifiers should be avoided.
Following these rules will help you create meaningful and valid identifiers that enhance the readability and maintainability of your code.
Examples of Keywords and Identifiers
Let’s look at some examples to understand the usage of keywords and identifiers in C:
In the above example, we have used keywords such as
return. These keywords define the structure and behavior of the program. On the other hand, identifiers like
printf are user-defined names that represent variables, arrays, and functions.
By using proper identifiers and keywords, you can write clear and concise code that is easy to understand and maintain.
Keywords and identifiers are integral parts of the C programming language. Keywords provide predefined meanings and functionalities, while identifiers allow programmers to create meaningful names for variables, functions, and other entities.
In this tutorial, we explored the complete list of keywords in C and discussed the rules for creating valid identifiers. By adhering to these rules and understanding the significance of keywords and identifiers, you can write efficient and error-free C programs.
Remember to choose meaningful and descriptive identifiers to enhance the readability of your code. Practice using keywords and identifiers in your programs, and gradually you will become comfortable with their usage.
Feel free to experiment with different examples and ask questions to solidify your understanding. Happy coding!
What are keywords in C?
Keywords in C are reserved words that have predefined meanings and cannot be used as identifiers for variables, functions, or any other user-defined names. Examples of keywords in C include 'int', 'if', 'while', 'for', etc.
What are identifiers in C?
Identifiers in C are user-defined names used to identify variables, functions, structures, or any other entities in a program. An identifier can consist of letters, digits, and underscore symbols, but it must start with a letter or an underscore.
How are keywords and identifiers different in C?
Keywords are reserved words with predefined meanings in C, while identifiers are user-defined names that represent variables, functions, or other entities. Keywords cannot be used as identifiers, but identifiers can be chosen by the programmer based on their needs, as long as they follow the rules for naming identifiers.
Can identifiers be used as keywords in C?
No, identifiers cannot be used as keywords in C. Keywords have predefined meanings and are reserved for specific purposes in the language. Using an identifier as a keyword would lead to a conflict and result in a compilation error.
What is the importance of keywords and identifiers in C?
Keywords and identifiers play crucial roles in programming with C. Keywords provide a set of predefined functionality and structure to the language, enabling programmers to use them for specific purposes. Identifiers, on the other hand, allow programmers to create and name user-defined entities, enhancing the readability and understandability of the code.