After the declaration of variables, your computer knows how much space is to be allocated for each
variable, but the actual value of this variable is not known. Although some F77 compilers implicitly
assign each declared variable a zero value or an empty string (for character types), I
strongly advise you not to count on it!
Definition of a variable is the same as assigning it a value. Assume that we have already declared
integer count, real result, logical flag, character*10 univ. The
definition of these variables occurs always after their declaration by assigning them their
actual values:
count = 0
result = 5.3
flag = .false.
univ = 'upenn'
These statements store zero in count, 5.3 in result, logical value 0 (.false.)
in flag and the string upenn in variable univ. Similar statements can
also be used to define variables of other data types.