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# 2. Errors in logic

Look at the following sentence:

My pencil just rode a bike to London

While it is a grammatical sentence, it makes no sense. Pencils don't ride bikes. Somewhere, the programmer writing this sentence has made a logical error. Only the programmer can spot these logic errors because the computer will just do exactly as it has been told.

Here are some very common logic errors.

#### Infinite loops

This pseudocode has a logic error

```                 Line 30:            mynumber = 1
Line 31:              WHILE mynumber != 2
Line 32:                PRINT mynumber
Line 33:              END WHILE

```

The mynumber variable is set to 1 in line 30, and nothing ever changes it - so the code loops around forever. The code below guarantees the while loop can end because of the increment mynumber command at line 33

```                 Line 30:            mynumber = 1
Line 31:              WHILE mynumber != 2
Line 32:                PRINT mynumber
Line 33:                INCREMENT mynumber
Line 33:              END WHILE

```

Challenge see if you can find out one extra fact on this topic that we haven't already told you

Click on this link: What are some examples of logic errors in programming?