The following common COBOL data types are discussed below:

  • Binary
  • Computational (comp)
  • Comp-1
  • Comp-2
  • Comp-3
  • Packed Decimal

Specified for binary data items. Such items have a decimal equivalent consisting of the decimal digits 0 through 9, plus a sign. Negative numbers are represented as the two’s complement of the positive number with the same absolute value.  The amount of storage occupied by a binary item depends on the number  of decimal digits defined in its PICTURE clause:

Digits in PICTURE Clause Storage Occupied
1 through 4 2 bytes (halfword)
5 through 9 4 bytes (fullword)
10 through 18 8 bytes (doubleword) │
The leftmost bit of the storage area is the operational sign.

Specified for internal decimal items. Such an item appears in storage  in packed decimal format. There are 2 digits for each character  position, except for the trailing character position, which is  occupied by the low-order digit and the sign. Such an item can  contain any of the digits 0 through 9, plus a sign, representing a  value not exceeding 18 decimal digits.

The sign representation uses the same bit configuration as the 4-bit  sign representation in zoned decimal fields.

Representation of the COMPUTATIONAL phrase is system-dependent and is  normally assigned to representations that yield the greatest  efficiency when arithmetic operations are performed on that system.

Specified for internal floating-point items (single precision).  COMP-1 items are 4 bytes long. The sign is contained in the first bit  of the leftmost byte and the exponent is contained in the remaining 7  bits. The last 3 bytes contain the mantissa.

Specified for internal floating-point items (double precision). COMP-2 items are 8 bytes long. The sign is contained in the first bit  of the leftmost byte and the remaining 7 bits contain the exponent.  The remaining 7 bytes contain the mantissa.

COMPUTATIONAL-3 or COMP-3 (internal decimal)
For VS COBOL II, this is the equivalent of PACKED-DECIMAL.

COMPUTATIONAL-4 or COMP-4 (binary)
For VS COBOL II this is the equivalent of BINARY.

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