ea

du3/program.c

@@ -5,6 +5,55 @@
 #include<time.h>
 #include<stdlib.h>
 
+#define max_yr 9999
+#define min_yr 1900
+
+int isleap(int y) {
+   if (y % 4 != 0) {
+      return 0;
+   } else if (y % 100 != 0) {
+      return 1;
+   } else if (y % 400 != 0) {
+      return 0;
+   }
+
+   return 1;
+}
+
+int datevalid(int d, int m, int y) {
+   if(y < min_yr || y > max_yr) {
+      return 0;
+   }
+   
+   if(m < 1 || m > 12) {
+      return 0;
+   }
+   
+   if(d < 1 || d > 31) {
+      return 0;
+   }
+
+   if(m == 2) {
+      if(isleap(y)) {
+         if(d <= 29) {
+            return 1;
+         }
+      } else {
+         return 0;
+      }
+   }
+
+   if ( m == 4 || m == 6 || m == 9 || m == 11 ) {
+      if(d <= 30) {
+         return 1;
+      } else {
+         return 0;
+      }
+   }
+
+   return 1;
+}
+
 int main() {
    char buffer[20];
    struct tm tm = {0};
@@ -18,7 +67,7 @@ int main() {
 
    retval = strptime(buffer, "%e.%m.%-Y", &tm);
 
-    if (retval == 0) {
+   if (retval == 0 || datevalid(tm.tm_mday, tm.tm_mon + 1, tm.tm_year + 1900) == 0) {
       puts("Neplatny datum");
       return 0;
    }
@@ -26,7 +75,10 @@ int main() {
    tm.tm_isdst = -1;
    tm.tm_mday += 7;
 
-    mktime(&tm);
+   if (mktime(&tm) == -1) {
+      puts("Neplatny datum");
+      return 0;
+   }
    
    strftime(buffer, sizeof(buffer), "%e.%m.%-Y", &tm);
    puts(buffer);