# math operations on time variables

if i have 2 time variables:

```    a = 00:00:12 and b = 00:00:05
```

how would i add them together to make :

```    c = 00:00:17 ?
```

then i need to divide them to crate an average, but im stuck on the add part.

i get the data from the database in this format and when i try a simple :

```    c=a+b;
```

i get :

```    00
```

how do i implement simple math operations on a time variable?

Or you simply go straight forward ;-)

```<?php
\$a = "00:00:12";
\$b = "00:00:05";

\$timeAcomponents = explode(":", \$timeA);
\$timeBcomponents = explode(":", \$timeB);

\$timeAinSeconds = \$timeAcomponents[0]*60*60 + \$timeAcomponents[1]*60 + \$timeAcomponents[2];
\$timeBinSeconds = \$timeBcomponents[0]*60*60 + \$timeBcomponents[1]*60 + \$timeBcomponents[2];

\$timeABinSeconds = \$timeAinSeconds + \$timeBinSeconds;

\$timeABsec = \$timeABinSeconds % 60;
\$timeABmin = ((\$timeABinSeconds - \$timeABsec) / 60) % 60;
\$timeABh = (\$timeABinSeconds - \$timeABsec - \$timeABmin*60) / 60 / 60;

}

echo "\$a + \$b = ".addTime(\$a, \$b);
?>
```

```\$date['first'] = DateTime::createFromFormat('H:i:s', "00:00:12");
\$date['second'] = DateTime::createFromFormat('H:i:s', "00:00:05");

\$interval = new DateInterval('PT'. \$date['second']->format('s') .'S');

echo \$date['first']->format('s'); // echoes 17
```

Just use mktime for all operations and then convert it back to readable format (using date) when you output dates:

```\$a = mktime(0, 0, 12);
\$b = mktime(0, 0, 5);

echo date('G:i:s', \$a + \$b);
echo date('G:i:s', (\$a + \$b) / 2);
```

In MySQL you can do it in this way -

```SET @a = '00:00:12';
SET @b = '00:00:05';

SET @a_sec = TIME_TO_SEC(@a);
SET @b_sec = TIME_TO_SEC(@b);

SET @c_sec = @a_sec + @b_sec;

SELECT SEC_TO_TIME(@c_sec);
+---------------------+
| SEC_TO_TIME(@c_sec) |
+---------------------+
| 00:00:17            |
+---------------------+
```

### Have I completed this C++ pointers / lists assignment?

Write a class ListNode which has the following properties: int value; ListNode *next; Provide the following functions: ListNode(int v, ListNode *l) int getValue();

### Getting the Max Value of One-To-Many a relation in CoreData through NSPredicatae

I'm creating a timeclock application where there is a ClockPunch NSManagedObject model with properties representing a clockin and clockout punch. Each ClockPunch instance has a relationship with an

### How to prevent jar decompilation

I have created a plugin project in Eclipse, distributed as a jar.