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  1. #include <ctime>
  2. #include <cstdio>
  3.  
  4. const char *months[]={
  5.                       "\nJanuary","\nFebruary","\nMarch","\nApril","\nMay","\nJune","\nJuly","\nAugust","\nSeptember","\nOctober","\nNovember","\nDecember"
  6.                      };
  7.  
  8. int month_days[] = {0, 31, 28, 31, 30, 31, 30, 31 ,31 ,30, 31, 30, 31};
  9.  
  10. int first_day_year(int year)
  11. {
  12.     int first_day;
  13.     int x;
  14.     int y;
  15.     int z;
  16.  
  17.     x = (year - 1.)/4.0;
  18.     y = (year - 1.)/100.;
  19.     z = (year - 1.)/400.;
  20.  
  21.     first_day = (year + x - y + z) %7;
  22.  
  23.     return first_day;
  24. }
  25.  
  26. int leapyear(int year)
  27. {
  28.      if((year% 4 == 0 && year%100 != 0) || year%400 == 0){
  29.           month_days[2] = 29; //agora [2] está certo devido ao primeiro ponto
  30.           return 1;
  31.      }
  32.  
  33.      //else é desnecessário basta fazer o retorno diretamente
  34.      return 0;
  35. }
  36.  
  37. int calendar(int month, int year, int first_day)
  38. {
  39.     int i;
  40.  
  41.     printf("%s %d\n\n", months[month-1], year); //month-1 para imprimir o correto
  42.     printf("Sun  Mon  Tue  Wed  Thu  Fri  Sat\n");
  43.  
  44.     for(i = 1; i < month; i++) //agora começa em 1
  45.     {
  46.         //+month_days[i] e não +month_days[month] que era o problema maior 
  47.         first_day = ((first_day + month_days[i])%7); 
  48.     }
  49.  
  50.     for(i = 1; i <= 1 + first_day * 5; i++)
  51.     {
  52.         printf(" ");
  53.     }
  54.  
  55.     for(i = 1; i <= month_days[month]; i++)
  56.     {
  57.         printf("%2d", i);
  58.  
  59.         if((i + first_day)%7 > 0)
  60.             printf("   ");
  61.         else
  62.             printf("\n ");
  63.     }
  64. }
  65.  
  66. int main(void)
  67. {
  68.     int year;
  69.     int month;
  70.     int first_day;
  71.  
  72.     do{
  73.         printf("Enter a month (1 - 12): ");
  74.         scanf("%d", &month);
  75.     } while (month < 1 || month > 12);
  76.  
  77.     do{
  78.         printf("Enter a year (1000 - 3000): ");
  79.         scanf("%d", &year);
  80.     } while (year < 1000 || year > 3000);
  81.  
  82.     first_day = first_day_year(year);
  83.  
  84.     leapyear(year);
  85.  
  86.     calendar(month, year, first_day);
  87.  
  88.     printf("\n");
  89.  
  90.     return 0; 
  91. }
Success #stdin #stdout 0s 16064KB
comments (?)
stdin 
2
2004
stdout 
Enter a month (1 - 12): Enter a year (1000 - 3000): 
February 2004

Sun  Mon  Tue  Wed  Thu  Fri  Sat
  1    2    3    4    5    6    7
  8    9   10   11   12   13   14
 15   16   17   18   19   20   21
 22   23   24   25   26   27   28
 29
https://ideone.com/MKiN7L
language:
C++ (gcc 8.3)
created:
7 years ago
visibility:
public

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