Leap years not working in Date and Time program in Dlang - date

Question

I haven't been programming very long, so I'm practicing some logic exercises in dlang. Any ideas on what I've done wrong here. When I get to a leap year, my program just keeps looping on the WHILE.
import std.stdio;
void main()
{
bool dead;
string thing;
int phew = 5; //days
int tahr = 1; //months
int tron; //monthsDate
string[7] days = ["Sunday", "Monday", "Tuesday", "Wednesday","Thursday", "Friday", "Saturday"];
int date = 28;
string[12] months = ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];
int year = 1996;
int hours = 11;
int mins = 28;
string ampm = "pm";
bool ly;
int leap = 1996;
int cen = 996;
//writeln("This program is incomplete. Obviously.");
write("Press Enter to Continue.");
readf("%s\n",&thing);
while(!dead)
{
while(hours <= 12)
{
while(mins <= 59)
{
if(mins < 10)
write(date," ",months[tahr],", ",year,". ",days[phew],". ",hours,":0",mins,ampm,": ");
else
write(date," ",months[tahr],", ",year,". ",days[phew],". ",hours,":",mins,ampm,": ");
readf("%s\n",&thing);
mins++;
}
hours++;
if(hours == 12 && ampm == "am")
{
ampm = "pm";
}
else if (hours == 12 && ampm == "pm")
{
ampm = "am";
phew++;
date++;
if(phew > 6)
phew = 0;
if((date == 29 || date == 30) && tahr == 1)
{
while(leap <= year) //this assuming time travel doesn't work
{ //reminder: add time travel
if (leap == year)
{
ly = true;
break;
}
leap+=4;
ly = false;
}
if(!ly || date == 30)
{
date = 31;
leap-=4;
}
}
if(!ly || date == 30)
{
date = 31;
leap-=4;
}
}
if(date == 31 && (tahr == 1 || tahr == 3 || tahr == 5 || tahr == 8 || tahr == 10))
{
date = 1;
tahr++;
}
else if (tahr == 11 && date == 32)
{
tahr = 0;
date = 1;
year++;
cen++;
if(cen == 1000)
{
writeln("Happy Millennium!");
cen = 0;
}
else
writeln("Happy New Year!");
}
else if(date == 32 && (tahr == 0 || tahr == 2 || tahr == 4 || tahr == 6 || tahr == 7 || tahr == 9))
{
date = 1;
tahr++;
}
}
if(hours == 13)
{
hours = 1;
}
mins = 0;
}
}
}
The important part is this:
if((date == 29 || date == 30) && tahr == 1)
{
while(leap <= year) //this assuming time travel doesn't work
{ //reminder: add time travel
if (leap == year)///
{
ly = true;
break;
}
leap+=4;
ly = false;
}
if(!ly || date == 30)
{
date = 31;
leap=-4;
}
}
So, I figured out the issue almost immediately after posting. Basically, I wrote =+ instead of +=. Very simple mistake. That's what I get for typing too fast. So, I've fixed up the code now, if you have any other suggestions, make sure to put them in the comments. Thanks.

Answer 1

Decided to print out leap into the terminal, and I figured out my issue. Leap was continuously equal to 4, because I wrote =+ instead of +=. It was just a case of clicking the wrong button first. That's what I get for typing fast. The program works now, as far as I know. Feel free to correct me on anything else you may notice.

Answer 2

I haven't read it in depth, but I recommend you add lots of debug writelns.
Particularly just inside the block you're THINKING should get run:
if((date == 29 || date == 30) && tahr == 1) {
writefln("Handling leap years...");
while(leap <= year) //this assuming time travel doesn't work
{ //reminder: add time travel
writefln("In loop, Leap <= year? %s", leap <= year);
This will allow you to debug more what is actually happening when your program is run.