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Power-Programmierung
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CD1.mdf
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pcmagazi
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1992
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08
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dow.c
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C/C++ Source or Header
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1991-12-30
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1KB
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49 lines
// dow.c
#include<stdio.h>
#include<stdlib.h>
int dow(int month, int day, int year)
{
const signed char calendar[12] =
{
0, 1, -1, 0, 0, 1, 1, 2, 3, 3, 4, 4 // base 30
};
return
(( ((year-1) * 365L) // # days of normal years, previous
+ ((year-1) / 4) // # of possible leap days
- (((year-1) / 100) // # of non-century leap days
- ((year-1) / 400)
)
// # of days in month passed
+ (calendar[month-1] + ((month-1)*30))
+ ((
((year % 4 == 0) && (year % 100 != 0)) || (year % 400 == 0))
&& (month > 2)
)
+ day)
% 7);
}
void main(int argc, char **argv)
{
int day, month, year;
const char *daystr[7] =
{ "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };
if(argc != 4)
{
printf("Enter date [mm dd yyyy]: ");
scanf("%d %d %d", &month, &day, &year);
}
else
{
month = atoi(argv[1]);
day = atoi(argv[2]);
year = atoi(argv[3]);
}
printf("%02d/%02d/%04d is on %s\n",
month,day,year, daystr[dow(month,day,year)]);
}