Code-and-Fix Model

Definition

The simplest (and oldest) software process: developers write code based on a rough idea, then fix problems as they're discovered, with no formal planning, design, or documentation phase.

Steps

1. Build a quick version of the product
2. Modify it (fix bugs/add features) until the customer is satisfied
3. Repeat step 2 as needed

  ┌─────────┐      ┌──────┐
  │  Code   │ ───▶ │ Fix  │ ───▶ (repeat)
  └─────────┘      └──────┘

Characteristics

• No requirements analysis or design phase
• No formal testing plan
• Documentation, if any, is an afterthought
• Fast to get something running initially

Advantages

• Very fast for small, simple, or throwaway programs
• Minimal overhead — good for prototypes, student projects, quick scripts
• No process overhead needed for trivial problems

Disadvantages

• Not scalable — becomes unmanageable as size/complexity grows
• Expensive to maintain — no design means every fix risks breaking something else
• No way to assess progress or quality objectively
• High risk of poor structure ("spaghetti code")
• Directly associated with causing the software crisis when used on large projects

When to Use

• Small, one-off scripts or experiments
• Prototypes meant to be discarded
• Never recommended for large-scale, production, or safety-critical software

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Exam tip: Often asked as "the oldest/most primitive model" — contrast directly with the Waterfall model's formal phases.