[NEED HELP]need help to solve a problem in calculating difference between time

[tanvir108115]

i need to save present date and time in text file when i input 1.and when i input 2 tha program needs to read that date and time from the file and compare it with present date and time and show the difference.i am trying for two days.but it is showing some wrong output.can some one solve the problem?thanx

#include <stdio.h>
#include <time.h>
struct save
{
    time_t t;
};

    int main(void)
    {
        int x;
        double sec;
        struct save a;
        struct tm * g,*h;
        time_t mytime;

        FILE *pfile;
        do
        {
            mytime=time(NULL);
        printf("1.Save 2.compare");

        scanf("%d",&x);
        if(x==1)

        {
            a.t=time(NULL);

            pfile=fopen("time.txt","wb");
            g = localtime (&a.t);
            printf ("Current local time and date: %s", asctime(g)); //showing current time and date
            fwrite(&a,sizeof(a),1,pfile);      //saving current time and date
            fclose(pfile);
        }
        else
        {
            pfile=fopen("time.txt","wb");
            fread(&a,sizeof(a),1,pfile);
            fclose(pfile);
            g = localtime (&a.t);
            printf ("Current local time and date: %s", asctime(g)); //showing the time from saved file

            h = localtime (&mytime);
            printf ("Current local time and date: %s", asctime(h)); //showing current time and date

            sec=difftime(mytime,a.t);  //calculating difference
            printf("difference = %f",sec);
        }

        }while(x!=3);
        return 0;
    }

[WoodSTokk]

i need to save present date and time in text file when i input 1.and when i input 2 tha program needs to read that date and time from the file and compare it with present date and time and show the difference.i am trying for two days.but it is showing some wrong output.can some one solve the problem?thanx

[…]
        else
        {
            pfile=fopen("time.txt","wb");
            fread(&a,sizeof(a),1,pfile);
            fclose(pfile);
[…]

You open the file for 'wb' (write binary). That means that the content of the file will truncated and the read/write-pointer stay at position 0.
And you should check if the file is successfull opened.