sap ag csu chico mins298c abap/4 programming introduction to data types chapter 4 fall 1998

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MINS298c ABAP/4 Programming

Introduction to Data Types

Chapter 4

Fall 1998

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Overview

Introduction

Declaration

Data Types

elementary

complex

Working with Data Types

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Data Objects

Data Object

VariableFixed

? ?

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Data Objects

Data Object

VariableFixed

Literals Constants

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Fixed Data Objects (Constants and Literals)

CONSTANTS: company_name(3) type c value ‘SAP’.

Literals are inside quotes

WRITE: ‘Happiness is SAP’.

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Hierarchy

Variable Data Objects

Table Record Field

Table is made up of Records(s) is made up of have a structure Field(s) is made up of characters have a type

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Fields are Variables

may be declared at any point within the program

may use up to 30 characters in name

may use hyphen, but prefer dash for readability

may not use an ABAP reserved word

follow rules of scope definition

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Normal Scope

ProgramDATA A, B, C

FormDATA X, Y, Z

FormDATA D, E, F

Write A Write F

Write AWrite F

Write AWrite F

According to normal rules of “scope,” whichWrite statements are legal and which are not?

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Data Types

User definedPre-defined

(p,i,f,c,n,d,t,x)

Elementary Structured

Structured type Table type

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Data Types

User definedPre-defined

(p,i,f,c,n,d,t,x)

Elementary Structured

Structured type Table type

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Pre-defined Types(with default length and value) Character Default Justify

c 1 space left n 1 ‘0’ left

Numbers i 4 0 right

p 8 0 right f 8 0.0 right

Date (d) 8 ‘00000000’ left

Time (t) 6 ‘000000’ left

Hexadecimal (x) 1 ‘00’ left

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Data Types

User definedPre-defined

(p,i,f,c,n,d,t,x)

Elementary Structured

Structured type Table type

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Three Ways to Declare Types

pre-defined elementary types

non-elementary types

existing fields

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Types and Data Statement

DATA var[(length)] [TYPE type] [DECIMALS num] [VALUE init]

TYPES BEGIN OF rec-name

[fieldname]…

END OF rec-name

DATA var LIKE table-field [VALUE init]

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Similar Declarations

Data: customer_name(25) type c,

vendor_name(25) type c.

TYPES name(25) type c.

DATA: customer_name type name,

vendor_name type name.

DATA: customer_name(25) type c,

vendor_name LIKE customer_name.

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What are the defaults here?

What are the default type and length of ‘flag’ and of ‘my_number’?

DATA: flag, my_number.

What is contained in ‘c_alpha’ and ‘n_alpha’?

DATA: c_alpha(3) type c value ‘5’,

n_alpha(3) type n value ‘5’.

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Character: C vs N

C = justifies left and has trailing blanks

N = justifies right and has leading zeroes

What happens with:

DATA: var-1(4) type c value ‘1234’,

var-2(4) type n value ‘1234’.

WRITE:/ var-1, var-2.

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What are the defaults here?

What is contained in ‘c_alpha’ and ‘n_alpha’?

DATA: c_alpha(3) type c value ‘5’,

n_alpha(3) type n value ‘5’.

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Numbers

i - cannot have explicit length

p - 15 digits, can explicitly define decimal places

DATA Dollars TYPE p DECIMALS 2.

f - handles exponential, subject to rounding errors

sometimes (1.0/3.0)*3.0 is not 1.0

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Dates and Times

Date = d stored as YYYYMMDD with initial value of 00000000

Time = t stored as HHMMSS with 000000

Why store in this format?

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Which is easier to sort?

01/01/58

01/20/58

01/01/60

12/01/97

01/20/00

19580101

19580120

19600101

19971201

20000120

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Computations on Dates

DATA my_date LIKE sy-datum.

MOVE 19580420 to my_date.

my_date = my_date - 1.

Write:\ my_date.

Displays 19580419

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Offset and Length Format

One may address sub-parts of elementary data objects by specifying the offset and length !!!

MOVE sy-datum+6(2) to hold_day

1 9 5 8 0 4 2 0

sy-datum(0) sy-datum(6)

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Parameter Statement

Parameter statement creates a set of variable fields which are presented to the user for input on the selection screen.

PARAMETERS var TYPE type [DEFAULT value]

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Data Types

User definedPre-defined

(p,i,f,c,n,d,t,x)

Elementary Structured

Structured type Table type

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Records

records or structures are called field strings in ABAP

use BEGIN OF and END OF

nesting is allowed

use TYPES command

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Field String Types

TYPES : BEGIN OF ADDRESS,

street(20) type c,

city(20) type c,

state(10) type c,

zip type I,

END OF ADDRESS.

How large (in characters) is the record ADDRESS?

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Using Field String TypesTYPES : BEGIN OF ADDRESS,

street(20) type c,

city(20) type c,

state(10) type c,

zip type I,

END OF ADDRESS.

DATA: Old_Address TYPE Address,

New_Address TYPE Address.

MOVE Old_Address to New_Address.

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Using Field String TypesTYPES : BEGIN OF ADDRESS,

street(20) type c,

city(20) type c,

state(10) type c,

zip type I,

END OF ADDRESS.

DATA: Old_Address TYPE Address,

New_Address TYPE Address.

Old_Address

Street City State Zip

Old_Address-Zip

Old_Address-City

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Data Types

User definedPre-defined

(p,i,f,c,n,d,t,x)

Elementary Structured

Structured type Table type

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Creating Tables

Use the occurs statement

not necessary to identify the amount, may use zero (0).

Format

TYPES tablename TYPE type OCCURS 0.

Example

TYPES Address_Table TYPE ADDRESS OCCURS 0.

Really creates the structurewhich will be allocated andmaintained dynamically.

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Declarative Statements

DATA

TYPE

CONSTANTS

PARAMETERS

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Assignments

Create program(s) to

demonstrate the justification difference between the n and c types

determine whether or not our system has a rounding error in the fixed point arithmetic

find the difference between the current date and your birthday

prove that one day before 01/01/98 is 12/31/97 using the ABAP date types

use the parameter statement to interactively ask for two dates and display the difference between them.