Conducting ios::out & ios::in meanswhile will lead to something wrong.

When I declcared a variable of fstream and opened a file within my work directory with “ios::in | ios::out”, something wrong occured.

• Just only a sort of operation(i/o) can be done normally, and another one can not be done in a normal way.
• The sort operation can be done deponding on the calling order of reading / writing. If reading is run before writing, the reading gonna be successul, but the writting gonna be wrong.

When I separately declare an ifstream and an ofstream variable, and then, the issue was solved.

• Things go allright.

Here is the source code leading something wrong.
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