How many times can time variables be delcared?

This is a discussion on How many times can time variables be delcared? within the C++ Programming forums, part of the General Programming Boards category; Hi, Iam trying to compare to random dates/times but am unable to create 2 independent times as it wont let ...

  1. #1
    Qui
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    How many times can time variables be delcared?

    Hi, Iam trying to compare to random dates/times but am unable to create 2 independent times as it wont let me decalre 2 individual time_t variables, it will just overight the first variable with the second one.

    Is it not possible to create 2 indivudual random dates/time based on systemtime modify one and the other is not changed?

    If it is possible could someone tell me how I am to initialise it correctly, as at the momoent I am using:

    Code:
    #include<iostream>
    #include<string>
    #include<time.h>
    
    using namespace std;
    
    int main()
    {
        char t1[123];
        char t2[123];
        time_t time1 = time(NULL);
        time_t time2 = time(NULL) + (a constant);
        tm *ltime1 = gmtime(&time1);
        tm *ltime = gmtime(&time2);
        strtime(t1,123,"%a,%b,%Y", ltime1);
        strtime(t1,123,"%a,%b,%Y", ltime2);
        cout<<t1<<endl;
        cout<<t2<<endl;
        return 0;
    }
    Thanks

  2. #2
    and the hat of wrongness Salem's Avatar
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    gmtime() returns a pointer to its OWN internal memory (its always the same pointer)
    You need to copy the result, not just point at it
    Code:
        tm ltime1 = *gmtime(&time1);
        tm ltime2 = *gmtime(&time2);
        strtime(t1,123,"%a,%b,%Y", &ltime1);
        strtime(t2,123,"%a,%b,%Y", &ltime2);
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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  3. #3
    Qui
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    Thanks Salem I understand now, your a life save.

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