Manipulation de temps comment ça march?

fscanf(f,......,varible_de_type_time_t);

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main()
{
    int dure;
    time_t temps;
	struct tm pret;
	FILE* fpret=NULL;
	fpret=fopen("f.txt","a+");
	temps=time(NULL);
    pret=*localtime(&temps);
    fprintf(fpret, "%d\n%d\n%d\n",pret.tm_mday,pret.tm_mon+1,pret.tm_year+1900);
    printf("La dure (jours): ");
    scanf("%d",&dure);
    temps=time(NULL)+dure*3600;
    pret=*localtime(&temps);
    fprintf(fpret,"%d\n%d\n%d\n",pret.tm_mday,pret.tm_mon+1,pret.tm_year+1900);


    return 0;
}