SAP ABAP | Loop Control

Last Updated : 06 Oct, 2023

Introduction to Loop Control in SAP ABAP

In SAP ABAP programming, loop control is an essential concept that allows you to execute a block of code multiple times. This is especially useful when processing data in an efficient manner. Loops help automate repetitive tasks and handle large datasets effectively. In ABAP, there are various types of loops available to suit your specific requirements.

Types of Loops in ABAP

1. WHILE Loop

The WHILE loop keeps running as long as a specific condition remains true. It checks the condition before each iteration.

Syntax:

WHILE counter <= 10.
WRITE: / counter.
Add 1 to counter.
ENDWHILE.

In this example, the loop continues to iterate as long as the counter variable remains less than or equal to 10. The loop prints values ranging from 1 to 10.

2. Do Loop

The Do loop is designed to execute at least once and then checks a condition to determine whether it should continue iterating. The condition is checked after each iteration.

DO.
WRITE: / counter.
ADD 1 TO counter.
IF counter > 10.
EXIT.
ENDIF.

ENDDO.

This example prints values from 1 to 10, and the loop exits when the counter exceeds 10.

3. Nested Loops

Nested loops are a valuable tool when you need to iterate within another loop. They come in handy for processing hierarchical data or performing intricate operations.

DO 3 TIMES.
DO 2 TIMES.
WRITE: / sy-index, sy-index1.
ENDDO.
ENDDO.

In this code snippet, there is a nested loop structure called a Do loop. The outer loop iterates three times, and for each outer iteration, the inner loop iterates twice. This results in a total of six iterations overall.

Loop Control Statements

1. CONTINUE Statement

The CONTINUE statement skips the current iteration and proceed to the next iteration.

DO 10 TIMES.

IF sy-index = 5.

CONTINUE.

ENDIF.

WRITE: / sy-index.

ENDDO.

In this example, if the sy-index is 5, the CONTINUE statement will skip that particular iteration and proceed to the next one.

2. CHECK Statement

The CHECK statement is used to verify a condition within a loop. If the condition evaluates to false, the loop will be exited.

DO 10 TIMES.

indes = index +1.

CHECK index BETWEEN 4 and 8 .

WRITE: / index.

ENDDO.

When the value of index reaches between 4 and 8, the CHECK statement will print the index. the output of the above code will be (4, 5, 6, 7, 8).

3. EXIT Statement

The EXIT statement offers a way to stop and exit from a loop, regardless of the current condition of the loop. This provides control over how the loop is executed.

DO 10 TIMES.

IF sy-index = 5.

EXIT.

ENDIF.

WRITE: / sy-index.

ENDDO.

In this example, the loop is abruptly terminated when sy-index reaches 5, regardless of any ongoing conditions of the loop.

Practical Examples

Practical examples of loop control in SAP ABAP could be scenarios such as:

Receiving and processing customer orders from the database table.
Calculating and updating employee salaries based on established rules.
Scanning and validating data from external files.

These models are usually tailored to the specific needs of your ABAP system.

Best Practices in Looping

Optimization of loop performance is important in ABAP development. Here are some best practices:

Reduce the number of database accesses in the loop to reduce overhead.
Use the appropriate loop type depending on the situation (WHILE, DO, or nested loops).
Keep loops short and focused to increase code readability.
Use loop control statements judiciously, only when necessary.
Use indexing and table operations correctly when working with internal tables.

Conclusion

Loop control is an important concept in SAP ABAP, it allows you to repeat code execution more efficiently. Understanding the types of loops and control statements, and following best practices, ensures that your ABAP system works properly and can be maintained to support the needs of your SAP applications

SAP ABAP | While Loop

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