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However, note that performance suffers when there are more than 100 alternatives. Placing common values earlier in the list of cases can cause the function to execute significantly faster. For each case, either side of the equals sign "=" can be a simple string, a call to a parser function (including #expr to evaulate expressions), or a ...
The switch parser function, coded as "#switch", selects the first matching branch in a list of choices, acting as a case statement. Each branch can be a value , an expression ( calculation ), or a template call, [ 1 ] evaluated and compared to match the value of the switch.
Optimizing compilers such as GCC or Clang may compile a switch statement into either a branch table or a binary search through the values in the cases. [6] A branch table allows the switch statement to determine with a small, constant number of instructions which branch to execute without having to go through a list of comparisons, while a ...
Switch statements can allow compiler optimizations, such as lookup tables. In dynamic languages , the cases may not be limited to constant expressions, and might extend to pattern matching , as in the shell script example on the right, where the *) implements the default case as a glob matching any string.
Examples of, and arguments for, Jump Tables via Function Pointer Arrays in C/C++; Example code generated by 'Switch/Case' branch table in C, versus IF/ELSE. Example code generated for array indexing if structure size is divisible by powers of 2 or otherwise. "Arrays of Pointers to Functions" by Nigel Jones
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In such case it is always possible to use a function call, but this can be cumbersome and inelegant. For example, to pass conditionally different values as an argument for a constructor of a field or a base class, it is impossible to use a plain if-else statement; in this case we can use a conditional assignment expression, or a function call ...
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