## Monday, 16 December 2019

### What is CPU Usage and Memory Usage?

CPU Usage- It is the "amount of time" a CPU was used for processing the given instructions.

Memory Usage- It is the "amount of RAM" was used for processing the given instructions

Entry Processes- It is number of scripts are running at a single time. One entry process take fraction of a second to complete. So in 10 entry process you can have 10-30 visitors.

Number of Processes- It is number of process(script) can run in one time. One process take time till the execution of script.

I/O Usage- It is speed of data transfer between the hard disk and the RAM.

Question: Is high CPU usage bad?
If the CPU usage is around 100%, this means that your computer is trying to do more work than it has the capacity. Always CPU usage must be less than 90%, If so increase the CPU.

## Saturday, 14 December 2019

### How to add number of days to a date in PHP?

Program Example
```\$Date = "2020-09-19";
echo date('Y-m-d', strtotime(\$Date. ' + 1 days'));
echo date('Y-m-d', strtotime(\$Date. ' + 2 days'));
```

Output
```2020-09-18
2020-09-19
```

Question: How to add number of days to a current date?
```echo date('Y-m-d', strtotime("+10 days"));
```

It would add 10 days to the current date.

Question: How to subtract number of days to a current date?
```echo date('Y-m-d', strtotime("-10 days"));
```

It would subtract 10 days to the current date.

Question: How to add number of days to a on given date?
```\$date = new DateTime('2016-12-14');
echo date('Y-m-d', (\$date->getTimestamp()+ (3600*24*10) )); //3600 = 1 hour
```

It would add 10 days to the current date.

Question: How to subtract number of days to a given date?
```\$date = new DateTime('2016-12-14');
echo date('Y-m-d', (\$date->getTimestamp()- (3600*24*10) )); //3600 = 1 hour
```

It would subtract 10 days to the current date.