Computer in this sence means anything electronic that can accept user input, process it and give out a desired output. Read more about computers here >>>
For you to know that your computer has been infected by virus; your computer will bare the following characteristics.
1. Slow perfomance
Some of these malicious softwares replicate files jaming or flooding the computer network or memory hence slowing down its speed.
2. Erratic computer
When a virus finds its way on to your computer, programs will display irrelevant error messages and even block you from accesing accounts you have rights over.
3. Unexplained data loss
Virus will also reformatt harddisk or simply damaging programs hence you wake up one morning & find your important files have gone missing. Or, you insert a flash disk into computer ports only to find all contents erased.
4. Frequent crashing
This happens especially when significant damage has been made on computer system by sapping the memory.
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Androids do not get affected by virus unless you install it yourself so… just uninstall that app