Loan Management System – CSV based

A **Loan Management System** is a simple Python console application that helps store and manage customer loan records for a bank/financial institution. It keeps borrower details in a **CSV file (`loan.csv`)**, making the data lightweight, portable, and easy to inspect/edit.

This project supports:

• adding new customer loan records
• viewing all records
• searching by Customer ID
• modifying existing records
• deleting one record (or all records)
• calculating loan interest & total repayment (simple interest)

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Features (Menu Options)

1) Input Record

Add one or more customers to the system. For each customer, the program captures:

• Customer ID (unique numeric identifier)
• Name (alphabetic words)
• Loan Amount (principal)
• Loan Time (duration in months)
• Interest Rate (percentage)

Records are appended to loan.csv.

2) Display Records

Prints all stored customer records in a readable format.

If the file contains only headers (no data), it shows:

No records found. Please add customer records first.

3) Search Record

Searches for a single customer record by Customer ID and displays all details. If not found:

Record Not Found!

4) Modify Record

Updates an existing customer record by Customer ID.
All fields can be changed after validation, and the CSV is rewritten with updated values.

5) Delete Record

Deletes:

• a specific record by Customer ID, or
• all records by entering all (case-insensitive)

6) Calculate Loan

Calculates interest amount and total repayment for a given Customer ID using simple interest.

The program computes interest using months as time:

• interest = (principal * rate * time/12) / 100
• total_amount = principal + interest

7) Exit

Closes the program gracefully.

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Data Storage (CSV Backend)

All records are stored in loan.csv with the following header:

• CUSTOMER ID
• NAME
• LOAN AMOUNT
• LOAN TIME
• INTEREST

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Input Validation & Error Handling

The system is designed to fail safely and avoid crashing on invalid input.

Common validations

• Menu choice must be numeric and within 1–7
• Customer ID must be numeric (isdigit())
• Name must contain only alphabetic words (split() + isalpha())
• Loan Amount & Interest must be valid decimal numbers (float() via is_float())
• Loan Time must be numeric (months)

Empty file protection

Most operations first check whether records exist (beyond the header) before continuing.

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Functions Overview

Built-in / Library Modules Used

• os
  • os.path.exists() → checks if loan.csv exists
  • os.path.getsize() → checks if file is empty
• csv
  • csv.reader() → reads CSV rows
  • csv.writer() → writes rows back into CSV

User-Defined Functions

• no_records_check()
  Detects whether the CSV file has records beyond the header; prevents operations on empty datasets.

• heading()
  Ensures loan.csv exists and contains column headers.

• is_float(value)
  Returns True if value can be converted to float; else False.

• wrong_input()
  Standardized invalid input message + pause.

• data()
  Adds customer records after validating all fields.

• display()
  Displays all records.

• search()
  Finds and prints a record by Customer ID.

• modify()
  Updates a record by Customer ID and rewrites the CSV.

• delete()
  Removes a record by Customer ID or clears all records using all.

• calculate_interest()
  Retrieves a record and calculates interest + total repayment.

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How to Run

Requirements

• Python 3.x

Run the program

python loan_management_system.py

the program will create loan.csv if missing

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Made with ❤️ by empirea9