where n is any positive integer and each Vk is a variable. For example, the statement
READ (X, Y, A[1], B[1])
will input values into the four variables listed. For inputing values into an array, a statement such as the following might be used:
for I := 1 step 1 until 100 do READ (A[I]) .
The READ procedure inputs numbers and truth values. A number must be a legal Algol number (although an E may be substituted for the symbol ₁₀). For input into a Boolean variable, the truth values true and false are accepted; also, a non-negative number or a plus sign is interpreted as false and a negative number or a minus sign is interpreted as true. A blank is read as zero.
With the READ procedure, the type of a number on a data card does not have to be the same as the type of the variable to which it is assigned. Any necessary type conversions are done automatically. If N is the next number in the data, the statement
READ (V)
is equivalent to the statement
V := N .
The data cards are free field. The number of values per card, the length of numbers, and the number of spaces are arbitrary. A comma, however, must follow each number, including the last one on the last data card.