# the meaning of if ... then in computer science

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## 2 Replies - 1943 Views - Last Post: 16 July 2014 - 03:55 AM

### #1 leibniz76

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# the meaning of if ... then in computer science

Posted 16 July 2014 - 02:00 AM

I'm only familiar with one type of coding language, VBA for excel, and as far as I know the meaning of "if ... then" in that computing language is that it is not truth functional like the and or nor nand operators are. In that language if ... then meanings if you have a certain condition then you do something else. if ... then in computing languages does not have the same as it does in philosophical language where it is interpreted as:

T -> T = T
F -> T = T
F -> T = T
T -> F = F

However, since I'm only familiar with one language I want to get additional verification of this.

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## Replies To: the meaning of if ... then in computer science

### #2 cfoley

• Cabbage

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## Re: the meaning of if ... then in computer science

Posted 16 July 2014 - 03:10 AM

No. The philosophical thing you posted looks like a logical OR to me.

If ... else in most languages is for flow control.

```// This does A
if true
do A
else
do B

// This does B
if false
do A
else
do B
```

Most languages have something similar that conditionally evaluates expressions. Often it's called the ternary operator but some languages (like SML and LISP) use an if syntax. The one everybody uses is the IF function in Excel. Here is the ternary operation in action

```// a will be 1
a = true ? 1 : 2

// a will be 2
a = false ? 1 : 2
```

### #3 leibniz76

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• Posts: 89
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## Re: the meaning of if ... then in computer science

Posted 16 July 2014 - 03:55 AM

I got the truth table wrong. I meant:

T -> T = T
F -> T = T
F -> F = T
T -> F = F

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