CPP Identifiers

💻 C++ Identifiers (CPP Identifiers) – Complete Beginner to Interview Guide

In CPP Identifiers are the names given to program elements such as variables, functions, arrays, classes, and objects.
They help the compiler and programmer identify different entities in a program.

1️⃣ What is an Identifier? ⭐

An identifier is a user-defined name used to identify:

• Variables

• Functions

• Arrays

• Classes

• Objects

Example

📌 age and totalMarks are identifiers.

2️⃣ Rules for Identifiers in C++ ⚠️ (Very Important)

✔ Must start with a letter (a–z, A–Z) or underscore (_)
✔ Cannot start with a digit
✔ Can contain letters, digits, and underscores
✔ No spaces allowed
✔ Case-sensitive
✔ Cannot be a C++ keyword

Valid Identifiers

Invalid Identifiers ❌

3️⃣ Case Sensitivity in Identifiers ⭐

📌 value and Value are different identifiers.

4️⃣ Identifier Naming Conventions (Best Practices) ⭐⭐

Although not rules, these are recommended:

Camel Case

Snake Case

Constant Naming

5️⃣ Identifiers vs Keywords ⭐⭐

6️⃣ Identifier Scope ⭐

📌 Scope defines where an identifier can be used.

7️⃣ Common Identifier Errors ❌

❌ Using keywords as identifiers
❌ Starting name with number
❌ Using spaces or symbols
❌ Confusing case sensitivity

📌 Interview Questions (CPP Identifiers)

Q1. What is an identifier in C++?
👉 Name used to identify program elements

Q2. Can identifiers start with _?
👉 Yes

Q3. Are identifiers case-sensitive?
👉 Yes

Q4. Can we use keywords as identifiers?
👉 No

✅ Summary

✔ Identifiers name program elements
✔ Must follow naming rules
✔ Case-sensitive
✔ Cannot be keywords
✔ Good naming improves readability