IF "OR" multiple conditions - r

Question

I have a standard 2x2 table
Yes No
Yes a b
No c d
I want to create a condition whereby IF(a or b or c or d = 0) then 0.5 is added on to each of the cells a,b,c,d.
I have tried this:
if(a && b && c && d == 0){
a=a+0.5, b=b+0.5, c=c+0.5, d=d+0.5
}
But I am getting an error saying
Error: unexpected ',' in:
"if(a && b && c && d== 0){
a=a+0.5,"
i.e. I don't think it is letting me put multiple things to execute.
Also I don't think that the && is right between each of the letters as I believe that means IF(a and b and ...)
UPDATE TO QUESTION:
I have another related question.
If I have say a set of say n tables, all in the format:
Yes No
Yes a b
No c d
and if one of the a,b,c or d in any of the n tables is equal to zero then 0.5 is added on to each of the a,b,c,d for all of the n tables. How would I do that?
My list looks like the following:
n11 n12 n21 n22
1 188 1157 173 1168
2 2 201 1 101
3 369 2280 354 2289
4 1 61 0 61
5 1306 16870 1333 16773
6 4 81 3 79
7 6 117 5 118
8 19 334 15 318
9 1 49 0 48
10 0 36 1 33
11 2 114 3 113
12 13 433 37 696
13 1 64 0 65
14 4 157 1 160
15 1 42 0 43
16 1 150 5 146
17 7 1124 10 1117
18 2 78 2 77
and what I am trying to say is that if any of the aspects of the cells of the table are 0, then I want 0.5 to be added on to every cell.

Answer 1

In R you can't use , to separate line, but you can use ;.
Also, the way you are doing considers a,b and c are boolean (TRUE/FALSE), which is not the case as they are numbers. Your condition should be :
if (a == 0 || b == 0 || c == 0 || d == 0)
Note that your code will run nevertheless, even if a,b and c are not boolean since they are numbers and there is an equivalence between FALSE and a == 0. This means you could also write your condition as :
if (!a || !b || !c || !d)
For the UPDATE, I consider matList is the list of matrices :
for (ii in 1:length(matList())) {
if (any(matList[[ii]] == 0)) {
matList = lapply(matList, function(X){X+0.5})
break # Exit the for loop
}
}
lapply applies mat + 0.5 (i.e + 0.5 to each element of the matrix thanks to R sugar) to every element (here matrices) of the list matList and returns the resulting list.

Answer 2

The problem is with the commas that separate your variables. R syntax does not allow you to do it. Write it this way:
if (a && b && c && d == 0){
a=a+0.5
b=b+0.5
c=c+0.5
d=d+0.5
}
Another problem is that the behaviour you described does not match with your code. If you write && it means and, not or. If you want to check if each element is equal to 0, you should write the following:
Modified based on Rodrigo's comment, the correct code would be:
if (0 %in% c(a,b,c,d)){
a=a+0.5
b=b+0.5
c=c+0.5
d=d+0.5
}