Improved Email Address Validator using Structured Validation Rules

Address_Validator_Improved/README.md

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+# 📧 Improved Email Validator
+
+This project provides a structured email validation script written in Python.  
+It improves upon simple checks (like just searching for `@` and `.`) by applying multiple  
+rules to accurately determine whether an email address is correctly formatted.
+
+---
+
+## 🚀 Features
+
+### ✔ 1. Validates correct ordering of `@` and `.`
+- Ensures `.` appears **after** `@`.
+- Prevents invalid formats like:
+  - `abc.gmail@com`
+  - `@gmail.com`
+  - `abc@gmail.`
+
+### ✔ 2. Checks proper placement of characters
+- Local part (before @) must not be empty.
+- Domain must have a valid extension (like `.com`, `.in`, `.org`).
+
+### ✔ 3. Handles spaces, dots, and case sensitivity
+- Strips leading/trailing spaces.
+- Converts email to lowercase.
+- Detects consecutive dots such as `[email protected]`.
+
+### ✔ 4. Provides detailed error messages
+Instead of printing just “invalid”, the validator explains *why* the email is invalid.
+
+### ✔ 5. Uses regex + rule-based logic
+A hybrid approach ensures both flexibility and safety.
+
+---
+
+## 🧪 Example Output
+### Input
+
+[email protected]
+
+### Output
+
+✓ Email is valid!
+
+### Input
+
+@domain.com
+
+### Output
+
+✗ Email is invalid due to:
+ - Email must contain text before '@'.
+ - Email contains invalid characters or structure.
+
+##  How to Run
+
+```bash
+python email_validator.py

Address_Validator_Improved/address_validator_improved.py

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+import re
+
+def validate_email(email: str) -> dict:
+
+    result = {
+        "original_email": email,
+        "is_valid": True,
+        "errors": []
+    }
+
+    email = email.strip().lower()
+
+    # Rule 1: Email must not be empty
+    if not email:
+        result["is_valid"] = False
+        result["errors"].append("Email cannot be empty.")
+        return result
+
+    # Rule 2: Must contain exactly one '@'
+    if email.count("@") != 1:
+        result["is_valid"] = False
+        result["errors"].append("Email must contain exactly one '@' symbol.")
+        return result
+
+    local_part, domain_part = email.split("@")
+
+    # Rule 3: Local part must not be empty
+    if not local_part:
+        result["is_valid"] = False
+        result["errors"].append("Email must contain text before '@'.")
+
+    # Rule 4: Domain part must contain at least one '.'
+    if "." not in domain_part:
+        result["is_valid"] = False
+        result["errors"].append("Email must contain at least one '.' after '@'.")
+        return result
+
+    # Rule 5: Domain extension must be present
+    domain_name, *extensions = domain_part.split(".")
+    if not domain_name:
+        result["is_valid"] = False
+        result["errors"].append("Domain name cannot start with a dot.")
+
+    if any(ext == "" for ext in extensions):
+        result["is_valid"] = False
+        result["errors"].append("Email cannot end with a dot or contain empty extensions.")
+
+    # Rule 6: Prevent consecutive dots
+    if ".." in email:
+        result["is_valid"] = False
+        result["errors"].append("Email cannot contain consecutive dots '..'.")
+
+    # Rule 7: Basic character whitelist
+    allowed_pattern = r"^[a-z0-9._%-]+@[a-z0-9.-]+\.[a-z]{2,}$"
+    if not re.match(allowed_pattern, email):
+        result["is_valid"] = False
+        result["errors"].append("Email contains invalid characters or structure.")
+
+    return result
+
+
+if __name__ == "__main__":
+    print("------ Improved Email Validator ------")
+    user_email = input("Enter an email address: ")
+
+    response = validate_email(user_email)
+
+    if response["is_valid"]:
+        print("\n✓ Email is valid!")
+    else:
+        print("\n✗ Email is invalid due to:")
+        for err in response["errors"]:
+            print(f" - {err}")
+
+