Switch-Case vs. If/Else in C#: Does Choice of Conditional Statement Impact Performance?

C# Conditional Statements: switch-case vs. if/else - A Performance Analysis

This article examines the performance differences between switch-case and if/else statements in C#. A common question is whether the choice significantly impacts code efficiency. Let's clarify the misconceptions and explore the performance considerations.

IL and Runtime Performance: The Reality

The belief that switch-case and if/else drastically differ in performance is often inaccurate. In release mode, the compiler optimizes switch-case statements into efficient jump tables (MSIL 'switch'), leading to constant-time (O(1)) execution.

Compiler Optimizations: String Comparisons

A key optimization in C# involves string comparisons within switch-case. If the number of string cases surpasses a certain threshold, the compiler generates a hash table. This hash table lookup significantly outperforms the sequential string comparisons inherent in if/else structures.

Best Practices: When to Use Which

For improved efficiency, prioritize switch-case when handling numerous conditions (generally more than 5). With fewer conditions, the choice often boils down to code readability and developer preference. Readability should generally be favored unless performance profiling reveals a bottleneck.

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