C ++ delete a pointer using delete (1)

As we all know, when we use new to create a pointer, We must delete the pointer using delete after we use it. However, it is worth noting that it is just as simple as deleting this pointer? Next, we will use a program to illustrate this problem:

# Include
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Using namespace std;
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Int main ()
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{
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Int * p = new int;
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* P = 3;
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Cout <"value read by the pointer p after 3 is assigned to the p address:" <* p <endl;
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Delete p;
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Cout <"value read by pointer p after space deletion:" <* p <endl;
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Long * p1 = new long;
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* P1 = 100;
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Cout <"address saved in Pointer p after creating a new space:" <p <endl;
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Cout <"pointer to the new space p1 saved address:" <p1 <endl;
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* P = 23;
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Cout <"value read by the pointer p after 23 is assigned to the p address:" <* p <endl;
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Cout <"the value read by the pointer p1 after 23 is assigned to the address p:" <* p1 <endl;
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Delete p1;
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Return 0;
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}
In the above program, we will delete the pointer p using delete in row 8th. However, let's look at the output results of the program:

 

Compare the above program to analyze the output. First, we initialize a pointer p in row 5th of the program. Then output the value read by the pointer p. The program will certainly output 3 because of the 6th rows. Then, we deleted the pointer p in row 8th of the program. However, we are surprised to find that the value read by the pointer p can be output in the second row of the program. Didn't we delete it? Actually, debug ,: