Before you can start trying to apply the same operation to multiple variables by using arrays you need to first know what operation you want perform.
You cannot change the type of a variable, so to convert a character variable to a numeric variable you will need to make a new variable.
newvar = input(oldvar,32.);
So in order to convert multiple variables you could just replicate that statement, change the variable names.
newvar1 = input(oldvar1,32.);
newvar2 = input(oldvar2,32.);
newvar3 = input(oldvar3,32.);
If you want to try instead to use array then you will need two arrays. One for the original character variable and another for the new numeric variables.
array old oldvar1 oldvar2 oldvar3;
array new newvar1 newvar2 newvar3;
Now you can make a DO loop to index through the arrays and make the conversion.
do index=1 to dim(old);
new[index] = input(old[index],32.);
end;