Clever C ++

Today, my senior friend talked about the C ++ questions during the recruitment of the company. After listening to these questions, I felt that C ++ was untested. I really need to check out objective C ++. Of course, just share your feelings ....
1. The first is to exchange two data items. We usually use the third variable, so we can know at most how to exchange the real number without the third variable. What is the addition ~~~ But, said the senior brother, which method cannot be used, myGod. Is there a third method ~~~ If I go to the interview, I will die. So what is the method, that is, it can be an exclusive or, efficient, and can process any data type. As follows:

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2. >>># Swap two integer number
4. >>> A =10
6. >>> B =23
8. >>>Print "The A = {0}, B = {1} before swapping". Format (A, B)
10. The A =10, B =23Before swapping
12. >>> A ^ = B
14. >>> B ^ =
16. >>> A ^ = B
18. >>>Print "The A = {0}, B = {1} After swapping". Format (A, B)
20. The A =23, B =10After swapping

2. Global variables are placed in the heap, while local variables are placed in the stack, such as new and static variables that open up different or declarative variables are all placed in the heap. Therefore, a local pointer cannot be returned in a function, as shown in figure

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1. VoidFoo (Char* Pchar)
2. {
3. Pchar =New Char[10];
4. CharTempstr [] ="Hexiong";
5. Strcpy (pchar, tempstr );
6. Pchar [strlen (tempstr)] ='\ 0';
7. }

In this case, an error is reported. Of course, there are two solutions. The first one is to use reference ....

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1. VoidFoo (Char* & Pchar)
2. {
3. Pchar =New Char[10];
4. CharTempstr [] ="Hexiong";
5. Strcpy (pchar, tempstr );
6. Pchar [strlen (tempstr)] ='\ 0';
7. }

Second, use **

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1. VoidFoo (Char** Pchar)
2. {
3. * Pchar =New Char[10];
4. CharTempstr [] ="Hexiong";
5. Strcpy (* pchar, tempstr );
6. (* Pchar) [strlen (tempstr)] ='\ 0';
7. }

Of course, I prefer the first method .....

 

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