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Input/Output Statements
32
Input statements are used to read data into the program and output statements
are used to print or punch the results of calculations.
Consider the following mathematical problem
and assume that I,
J,
K, L, and M are variable quantities punched into a file of
cards, with N equal to 48. If you write the source statement
N
=
48
the processor sets aside an area in storage (in the object program) called N, and
sets up the necessary instructions to place the quantity 48 in that area at object
time. The variables may be punched into the cards as shown below .
:::,;..1.::
..:~;.
L:-:
;-' -- ;
~
"! "'I
..
'
K L M II
J
0000 0010 0000 0100 0000 000000000000000000000000000000000000000000000000000000000000
, ?
~
• 5618
9101112 1314151
17 18 19
~(j
~DaMn~"Mn~nnn~n~u~.~~Q~«~~o~~~nuu~~~u~~oo~~~~~~u~wm~nnM~."
••
~
1111 1111 1111 1111 1111 111111111111111111111111111111111111111111111111111111111111
2122 2221 2221 222 2 22 22 222222222222222222'-22222222222222222222222222222222222222222
3333 3 333 3333 3333 333 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 J 3 3 3 33 J3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
HI4 4144 4444 444. 4444 4 4 4 4 4 44 4 4 4 4 4 4 4 4 4 44 4 4 4 4 4
~ ~
4 4 4 4 4 4 4 4 44 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4
: :55 5555 5555 5555 5555
55555555"~5555555~555555555555555555555555555555555555555555
6G66 6666 6666 6666 6666
6666666666666666666666~G5666E6666666666666666666666666666666
*
~
7777 7777 7777 7777 7771 777777777777777777777177777777777777777777777777777 777777777
8888 8 8 8 8 8888 8888 8888 J 8 8
&
8 88 B 8 888 8 8 8 8 8
a
8 8 8 6 E 8 8 8 8 8 888 8 8 888
B
8 888 8 8 8 8 888 8 8 8 888 8 8 8 8 8 8
99 9 9 9999 9999 9999 9999
99:l~9999999999999999999S9S99999999SS9999999999999q9999999999
1234
5 S 1
e
9101112
!3
1~ ,~
:6
"
I~
,
j
20
11
22 2J 2'
~5
:r.
v
Z6
J9
3\. ',: ;'
33 14 35 3b 31 J8 39 40 41 41 4J 44 45 46 41 48 '9
so
51 52 5J 54 5S 56 5:
sa
59 60 61 62
GJ &4
65 66 67 68 69 0
/l
;~
IJ 14 15 16 11 78 19
8il
Remember that the data cards are not available while the source program is being
compiled. Therefore, in this example, an input statement would be included in
the source program to tell the processor that the object program will read the input
data from cards (that there will be five data fields in the sequence of K, L, M,
I, and
J).
The input statement also contains the statement number of another type
of statement called
FORMAT.
In this example, the
FORMAT
statement, referenced by
the input statement, tells the processor that each field named in the list is four col-
umns long and that the quantities are in fixed point mode. Thus, as the object
program is executed, each data card is read by the program and the quantity fields
are placed into the storage locations named K, L, M, I, and
J.
When processing is
completed for the set of values in one card, the values for the next card are read
into the same storage locations and processing for the new set of values is per-
formed.
Thus, an input or output statement, each with its corresponding
FORMAT
state-
ment specifies the number and sequence of the data input or output fields, the
length of the data fields, and whether they are in fixed or floating point mode.
NOTE:
FORMAT
statements are described in a later section entitled
SPECIFICATION
STATEMENTS.
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