problem description according to this entry code https: www.kancloud.cn inbuf... verifies there in Chapter 6 and finds that no matter whether the verification is correct or not, the error database table does not exist. At that time, I was not sure t...
problem description the environment is scientific computing software, and speed is very critical. for example, there is a class A { public: T* paired null; A () {} T* getP () {if (p = = NULL) p=new T (); return p;} ~ A () (if (paired null) {del...
id name relation 1 n1 r1 2 n2 r2 3 n4 r1 4 n5 r1 5 n6 r2 6 n6 r1 the relation relationship of the table is shown above where the relation field indicates the relationship between the cur...
Hello, everyone. I don t want to make a color run until the middle of the run, but the current situation is that the color color has already appeared before the color run is halfway through. I want to know how I should change my code until after the co...
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^ (18 [0-9] {9}) | (15 [0-9] {9}) $ Why the rule matches 1844444444444444 . My understanding of this rule is starting with 18 or 15 followed by 9 digits 0-9 . Note: I know there are other ways to write the rules of mobile phone numbers. I just ...