Identifiers

Introduction

Identifiers are names for variables, functions, and types. Rules: letters, digits, underscore; must not start with a digit; case-sensitive; cannot use keywords.

Understanding the topic

Valid names count, _temp, studentId2

Invalid names 2count, my-var, int (keyword)

Convention Use snake_case or camelCase consistently.

• Valid names — count, _temp, studentId2.
• Invalid names — 2count, my-var, int (keyword).
• Convention — Use snake_case or camelCase consistently.

Step-by-step explanation

1. Valid names — count, _temp, studentId2.
2. Invalid names — 2count, my-var, int (keyword).
3. Convention — Use snake_case or camelCase consistently.

Syntax reference

Syntax reference:

letter (letter | digit | _)*

Execution workflow

Best practices

• Enable warnings: gcc -Wall -Wextra -std=c11 source.c -o app
• Give every variable a defined value before it is read.
• Stay inside array bounds — C will not stop you from over-running a buffer.

Common mistakes

• Reading uninitialized storage — behavior is undefined.
• Dismissing compiler warnings instead of fixing root causes.
• Ignoring NULL returns from malloc, fopen, and similar APIs.

Hands-on exercise

Practice problems:

• List valid and invalid identifiers
• Rename ambiguous names

Summary

Identifiers in C — Naming rules for variables, functions, and types in C.