Switch 语句和条件运算符 c++

Question

My Q is why to use switch statement and the conditional operator when we have the (if else && else if)

Example 1:

unsigned short int any_number ;
any_number = ((15>0)? 10 : 5);//using here the conditional operator
if(15>0)//using if & else
any_number=10;
else
any_number=5;

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Example 2:

unsigned short int my_score;
std::cout << "what score you expect you got at the exam";
cin >> my_score;
switch(my_score)
{
case 90: 
std::cout<<"awesome keep the good work"; break;
case 80 :
std::cout<<"study harder next time"; break ;
case 20:
std::cout << "quit school"; break;
}

if(my_score==90)
std::cout<<"awesome keep the good work";
else if (my_score==80)
std::cout<<"study harder next time";
else if (my_score==20)
std::cout << "quit school";

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other than its costs less lines using swith and conditional operators i dont find them useful at all i like more the (if else) more it gives us more space can any one till me the diffrence if there is one?

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Answer 1

There are many reasons why we need switch statement, it is faster and cleaner(my opinion), but there is another reason: if you switch over an enum variable, and if you forgot to handle some enum values, the compiler can catch it for you.

c++ warning: enumeration value not handled in switch [-Wswitch]

Answer 2

main reason is readability

a long sequence of if elses is sometimes harder to read and maintain than a switch statement.

BTW the performance difference will surely disappear in production code created by a modern compiler.

The?: construct allows you to do thing not expressable in ifs

cout << (j>42?"a":"b")

for example

Answer 3

switch case is faster, for this point, you can use those two structures to write two functionally equivalent codes. and then compare the compiled assembly code: details you can refer to this: Efficiency analysis of switch and if else

Answer 4

Your main concern is code readability and how error-prone it is. For example, when not used with switch , case and break s (,), it's probably safer to go for if - else .

In C++ is it better to use switch and case statements or to use if statements? Personally I find the answers there as great as they are simple.