Switch-Case vs. If/Else in C#: When Does One Outperform the Other?

Performance comparison and best practices of Switch-Case and If/Else statements in C#

In C#, both switch-case and if/else statements are used to implement conditional execution logic. Despite the different syntax, developers often question whether there is a significant performance difference between the two.

Compilation and runtime performance

Compilation of the

if/else statement directly generates intermediate language (IL) instructions that perform conditional checks and branches. In release mode, switch-case statements are usually compiled into jump tables or hash tables.

The jump table optimizes performance by jumping directly to the corresponding branch, with a complexity of O(1). When switching strings, a hash table is used, which allows for fast lookup when there are a large number of case labels, but incurs additional overhead.

Best Practices

is based on performance characteristics, and the choice of switch-case and if/else depends on the number of conditions. For a small number of conditions (less than 5), the simplicity and readability of if/else may be preferred.

However, when the number of case labels is large, switch-case is more advantageous due to its efficient jump table or hash table optimization. This is especially noticeable when switching between string constants, where using a hash table for switch-case statements can significantly improve performance, while string comparisons within if/else blocks can degrade performance.

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