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Software Developer (SDE)

Software developers (often called SDEs or software engineers) design, write, test and maintain the code behind apps, websites and systems. Strong programming fundamentals, data structures and problem solving matter most, and they are what technical interviews test.

What the job involves

  • Turn product requirements into working, tested code.
  • Design classes, functions and data structures that are easy to change.
  • Read and review other people's code, and fix bugs.
  • Work with databases, APIs and version control as part of a team.

Core skills

  • One language in depth (Java, C++ or Python)
  • Data structures and algorithms
  • Object-oriented design
  • SQL and databases
  • Git and collaboration
  • Testing and debugging

Your learning path

Work through the steps in order. Each one links to the lessons and practice to use.

  1. Step 1: Learn one programming language well

    Pick Java, C++ or Python and learn its fundamentals properly: variables, conditions, loops, functions and input/output. Java and C++ are common in SDE interviews; Python is the easiest to start with. Learning C as well shows you how memory and pointers really work.

  2. Step 2: Master collections and core data structures

    Arrays, strings, lists, maps, sets, stacks and queues solve most everyday problems. Learn what each costs (Big O) and when to choose it.

  3. Step 3: Practise problem solving and algorithms

    Recursion, sorting, binary search, hashing, two pointers and sliding windows appear in almost every coding interview. Solve problems regularly and say the complexity of each solution.

  4. Step 4: Object-oriented design

    Classes, encapsulation, inheritance, interfaces and polymorphism are how large programs stay organized. Learn to model a problem with clean, small classes.

    Not on Laviyx Learn yet

    • Design patterns
    • SOLID principles

  5. Step 5: Databases and SQL

    Almost every application stores data. Learn to query, join and aggregate data, and understand keys, indexes and transactions.

  6. Step 6: Engineering practices

    Professional developers handle errors, write tests, use version control and understand concurrency basics.

    Not on Laviyx Learn yet

    • Git and GitHub
    • Unit testing (JUnit, pytest, GoogleTest)
    • System design basics

  7. Step 7: Prepare for interviews

    Revise concepts, practise explaining your answers out loud, and time yourself on coding questions.

Projects to build

Projects prove your skills and give you something to show.

  • A command-line expense tracker that saves data to a file.
  • A library or inventory system modelled with classes and collections.
  • A REST API backed by a SQL database.

Interview preparation

This path is a suggested order. Requirements differ between companies, so also read job descriptions for the roles you are applying to.

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