#include #include #include #include using namespace std; void dayOfTheWeek(int y, int m=1, int d=1){ //sec,min,hr,d[1,m[0,y-1900 tm input{0,0,0,d,m-1,y-1900}; time_t t = mktime(&input); int out = localtime(&t)->tm_wday; cout << (out==0 ? "Sunday" : out==1 ? "Monday" : out==2 ? "Tuesday" : out==3 ? "Wednesday" : out==4 ? "Thursday" : out==5 ? "Friday" : "Saturday" ) << endl; } //using Zeller's algorithm //bool print=false if we only want return value. int zAlgo(int yr, int m=1, int d=1, bool print=true){ if(m < 3){ m = m+12; yr--; } int y = yr % 100; int c = yr / 100; int wd = (d + floor((13*(m+1))/5)+y+floor(y/4)+floor(c/4)+(5*c)); wd = (wd-1) % 7; if(print){ cout << (wd==0 ? "Sunday" : wd==1 ? "Monday" : wd==2 ? "Tuesday" : wd==3 ? "Wednesday": wd==4 ? "Thursday" : wd==5 ? "Friday" : "Saturday") << endl; } return wd; } //other dates tested using assert void test(){ //bool print=0 for silent mode, no cout assert(zAlgo(1991,8,8,0) == 4); assert(zAlgo(2023,6,26,0) == 1); assert(zAlgo(1992,11,3,0) == 2); assert(zAlgo(2000,5,15,0) == 1); assert(zAlgo(1985,4,7,0) == 0); assert(zAlgo(2015,9,12,0) == 6); assert(zAlgo(2012,2,29,0) == 3); assert(zAlgo(1978,10,20,0)== 5); assert(zAlgo(2005,6,8,0) == 3); assert(zAlgo(1999,12,31,0)== 5); assert(zAlgo(2018,8,10,0) == 5); } int main(){ //inputs year, month, day //month, day default to 1 dayOfTheWeek(2023,6,27); zAlgo(2023,6,27); dayOfTheWeek(1900);//same as(1900,1,1) zAlgo(1900); dayOfTheWeek(2000); zAlgo(2000); dayOfTheWeek(2020); zAlgo(2020); test(); //more testing with cassert. }

C++DayOfTheWeek