Terminal Expense Ledger

Project roadmap

1. 01

   Define the commands and file format

   ~1h

   Write README.md: the commands (add AMOUNT CATEGORY [DESCRIPTION] [--date YYYY-MM-DD], list [--month YYYY-MM], summary [--month YYYY-MM]), the file format (one expense per line: date, amount in cents, category and description, separated by tabs), and the location of the file (an environment variable, or ledger.tsv in the current folder). Set up a CMake project with -Wall -Wextra. Done when: README.md defines the commands and file format.

2. 02

   Store expenses in memory

   ~1.5h

   Define a struct Expense (date as a string YYYY-MM-DD, amount in cents as long, category and description as fixed-size char arrays) and a dynamic array that grows with realloc. Write a function that parses an amount like 12.50 into 1250 cents carefully (checking digits, at most 2 decimals, and a positive value) without using floating point. Done when: unit tests show amounts are parsed correctly and bad ones are rejected.

3. 03

   Load and save the file

   ~1.5h

   Load the file with fgets and parse each line with strtok or sscanf, checking every field (a valid date, a number for the amount, and a category), and report bad lines with their line number instead of crashing. Append new expenses to the file with fopen in append mode. Done when: expenses added in one run are listed in the next, and a damaged line is reported.

4. 04

   Add and list expenses

   ~1.5h

   Implement add, using today's date from time and strftime unless --date is given (checked to be a real date), and validating the category (1 to 30 characters, no tabs). Implement list with aligned columns and amounts printed as 12.50, optionally filtered by month. Done when: adding and listing work with and without filters.

5. 05

   Print summaries

   ~1.5h

   Implement summary: totals per category, sorted by amount with qsort, with each category's share of the total, and totals per month, plus the grand total. Handle an empty ledger with a friendly message. Done when: the summary totals match the listed expenses.

6. 06

   Test it

   ~1.5h

   Write a test program (with assert) for amount parsing, date checking and totals, and a shell script that runs the program with a temporary ledger file through adding, listing, summarizing and bad input, comparing the output with expected files. Run it with valgrind or AddressSanitizer. Done when: the tests pass with no memory errors.

Resources

• DocsBeej's Guide to C Programming
• Docsrealloc (cppreference)
• Docsstrftime (cppreference)
• Docsqsort (cppreference)
• DocsCMake tutorial