Code Smell 221 - Missing Break in Switch

You abuse cases in switches and make subtle mistakes

TL;DR: Cases are GOTOs, but you might be missing them

Problems

• Hidden defects

• Readability

Solutions

1. Add the missing break

2. Convert the switch into a polymorphic hierarchy

3. Remove the default switch

Context

In a switch statement, when a match is found in a particular case, the code execution will start from that case and continue executing all subsequent cases until a break statement is encountered or the switch block ends.

This behavior is called "fall-through."

Forgetting a break clause will continue with the following case.

This is similar to a very serious vulnerability that implied an urgent release.

Sample Code

Wrong

  switch (number) {
      case 1:
          printf("Number is 1.\n");
          break;
      case 2:
          printf("Number is 2.\n"); 
          // Missing break
      case 3:
          // Case 2 will continue here
          printf("Number is 3.\n"); 
          break;
      default:
          printf("Number is not 1, 2, or 3.\n");
  }

// If the number is 2 this will output numbers 2 and 3

Right

  switch (number) {
      case 1:
          printf("Number is 1.\n");
          break;
      case 2:
          printf("Number is 2.\n"); 
          break; // Added 'break' to prevent fall-through
      case 3:
          printf("Number is 3.\n"); 
          break;
      default:
          printf("Number is not 1, 2, or 3.\n");
  }

// This is correct even though switches AND defaults
// Are other code smells

Detection

[X] Automatic

Many linters and also ChatGPT detect this smell.

Tags

• IFs

Conclusion

Using switches and causes is problematic, your need to use higher-level sentences.

Relations

Code Smell 110 - Switches With Defaults

Maxi Contieri ・ Dec 15 '21

#oop #cleancode #codesmells #tutorial

Code Smell 36 - Switch/case/elseif/else/if statements

Maxi Contieri ・ Nov 28 '20

#oop #webdev #tutorial #codenewbie

Code Smell 100 - GoTo

Maxi Contieri ・ Nov 6 '21

#poo #codesmell #cleancode #programming

More Info

Sonar Source

Common Weakness Enumeration

How to Get Rid of Annoying IFs Forever

Maxi Contieri ・ Nov 9 '20

#oop #programming #codenewbie #tutorial

Apple's Security Defect

Disclaimer

Code Smells are my opinion.

Credits

Photo by Nikola Johnny Mirkovic on Unsplash

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I am not terribly dogmatical about the goto statement. I have the uncomfortable feeling that others are making a religion out of it, as if the conceptual problems of programming could be solved by a single trick, by a simple form of coding discipline!

Edsger Dijkstra

Software Engineering Great Quotes

Maxi Contieri ・ Dec 28 '20

#codenewbie #programming #quotes #software

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This article is part of the CodeSmell Series.

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Maxi Contieri ・ May 21 '21

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