Question { NIT, 207094 }

What is the difference between online ups and offline ups?

Answer

The offline UPS is in standby mode. The charger is maintaining the battery, but the inverter stage is not running. Power goes from input to output, bypassing the inverter.
In this configuration, the charger and inverter design is less, as the charger is usually in trickle mode and the inverter does not need to run continuously. On power fail, the inverter starts up and takes the load. There is a glitch in output, a few line cycles, but most loads can handle this.
The online UPS runs all the time. The charger now runs the inverter, as well as maintaining charge on the battery. The inverter supplies the load. Power goes from input to charger to inverter to output.
In this configuration, the charger and inverter design is more, as they need to run continuously. On power fail, there is no glitch, because the inverter is already running and supplying the load. Usually, there is synchronization between the inverter and the line, so that failure of the inverter can initiate fall-back to the line without glitch.


Read more: http://wiki.answers.com/Q/What_is_the_Difference_between_off-line_and_online_UPS#ixzz1MJtsQvtb

Question { 11312 }

What is difference between str_replace and substr_replace

Answer

Difference between str_replace and substr_replace

str_replace —
Replace all occurrences of the search string with the
replacement string.

Example for str_replace()

echo str_replace("world","siva","Hello world!");
?>

substr_replace -

The function substr_replace introduces some additional
functionality to compliment str_replace. substr_replace is a
more mathematically based replace function, which relies on
starting points and lengths to replace parts of strings, as
opposed to searching and replacing.

Example for substr_replace()

//string that needs to be customized
$original = "ABC123 Hello Mr. siva! DEF321";

//starting point 5
$sp5 = substr_replace($original, "Five", 5);
//starting point 12
$sp12 = substr_replace($original, "Twelve", 12);
//starting point 0
$sp0 = substr_replace($original, "Zero", 0);
//starting point -1
$spneg1 = substr_replace($original, "Negative 1", -1);

//Echo each string
echo "Original String: $original
";
echo "Starting Point 5: $sp5
";
echo "Starting Point 12: $sp12
";
echo "Starting Point 0: $sp0
";
echo "Starting Point -1: $spneg1 ";