C++核心准则ES.70:进行选择时,switch语句比if语句好
ES.70: Prefer a switch-statement to an if-statement when there is a choice
ES.70:进行选择时,switch语句比if语句好
Reason(原因)
Readability.
可读性
Efficiency: A switch compares against constants and is usually better optimized than a series of tests in an if-then-else chain.
效率:switch语句执行的时常数比较运算,相比一系列if-then-else语句,通常可以更好地被优化。
A switch enables some heuristic consistency checking. For example, have all values of an enum been covered? If not, is there a default?
switch语句允许某些启发式检查。例如枚举类型的所有值是否都被覆盖到了?如果没有,是否设置的default选项?
Example(示例)
void use(int n)
{
switch (n) { // good
case 0:
// ...
break;
case 7:
// ...
break;
default:
// ...
break;
}
}
rather than(而不是):
void use2(int n)
{
if (n == 0) // bad: if-then-else chain comparing against a set of constants
// ...
else if (n == 7)
// ...
}
Enforcement(实施建议)
Flag if-then-else chains that check against constants (only).
标记和常数值进行比较的if-then-else判断链(只限于这种情况)
原文链接
https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#es70-prefer-a-switch-statement-to-an-if-statement-when-there-is-a-choice
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