PICTURE clause (and Data types in COBOL)

• PICTURE clause is used to specify the characteristics of the Elementary Data-Item such as Data-type, Sign, Decimal point location, Size etc.
• PICTURE clause can also be specified as PIC
• PICTURE clause can be used only with elementary data-item
• PICTURE clause cannot be used with group data item, 88 level number, USAGE IS COMP-1 & COMP-2
• Below is explanation of characteristics that can be defined using PICTURE clause:-
• Data Type: -
  • Any data-item can be of data-type: numeric, alphabetic, or alphanumeric.
  • The numeric data type can consists of only digits 0-9. This data type can be used for variables such as Price, Quantity, Total value
  • The alphabetic data type consist only of letters A-Z or a-z and the space(blank). This data type can be used for variables such as Name, Item Description etc.
  • The alphanumeric data type consist of digits, letters, space and special characters. This data type can be used for variables such as Address, Date etc.
  • These data type can be specified in PIC clause using code characters shown in table below:- here <LINK to code character table>
• Sign :-
  • A numeric data item can be either signed or unsigned
  • If considered unsigned then during program execution these data items are treated as positive quantities
  • Code character ‘S’ is used at the leftmost end of PIC clause to describe that data item is signed data item
  • Sign does not occupy extra space as it is stored at the zone bits(first four bits of a byte) of rightmost digit of data item.
• Decimal point location:-
  • Decimal point location can be specified for Numeric data item using code character ‘V’ PIC clause
  • If not specified numeric data item will be considered as integer
  • The position of decimal point is merely an assumed position and it is not explicitly included in data(i.e. it does not occupy space in storage)
• Size:-
  • The number of characters or digits required to store data item is known as Size of data item
  • There is no special code character to represent the size of data-item. Size can be specified by the repeated occurrence of representing code characters or by specifying number in parentheses. Example: - ‘PIC XXX’ means three character alphanumeric string. Same declaration can also be specified as ‘PIC X(3)’
• Below table describes the code characters that can be used to specify Data-type, Sign and Decimal point of Data-item

• Important points need to remember while using PIC clause:-
  • As specified above, there is no special code character to represent the size of data-item. Size can be specified by the repeated occurrence of representing code characters or by specifying number in parentheses. Example: - ‘PIC XXX’ means three character alphanumeric string. Same declaration can also be specified as ‘PIC X(3)’
  • The picture clause is only to be specified for elementary items; it cannot be used for a group item.
  • The occurrence of ‘V’, ‘P’ and ‘S’ are not counted in determining the size of an item.
  • The size of a group item is equal to the total of the sizes of all subordinate elementary items. The class of a group item is alphanumeric.
  • When specifying Alphabetic data item: the PIC must contain only code character ‘A’
  • When specifying Numeric data item: the PIC must contain only code character ‘9’, ‘S’, ‘V’ and ‘P’. The code character ‘V’ and ‘S’ can be specified only once. When used ‘S’ it must be at the leftmost position of PIC clause. The occurrence of code character ‘P’ can be repeated on the right or on left (but not on the left of S) as many times as is required to indicate the position of the assumed decimal point.
  • When specifying Alphanumeric data item :- the PIC may contain all Xs or a combination of 9, A and X(except all 9 or all A)
• Examples:-

• Apart from above mentioned Code Characters, there are few more Code chanracters which are mostly used while priniting/generating Reports. We will learn Editing Code chanracter and De-editing in next section