ABAP String Comparison: Equality, Case-Insensitive, Pattern Matching

In SAP ABAP, you can compare strings using different methods depending on the requirement. Here are the common ways:

1. Using `IF` for Simple Equality Comparison

DATA: lv_str1 TYPE string VALUE 'ABAP',
      lv_str2 TYPE string VALUE 'ABAP'.

IF lv_str1 = lv_str2.
  WRITE: 'Strings are equal'.
ELSE.
  WRITE: 'Strings are not equal'.
ENDIF.

This checks if both strings are exactly the same (case-sensitive).

2. Using `IF NOT` for Inequality

IF lv_str1 <> lv_str2.
  WRITE: 'Strings are different'.
ENDIF.

Checks if two strings are not equal.

3. Case-Insensitive Comparison (`TO UPPER CASE`)

DATA: lv_str1 TYPE string VALUE 'ABAP',
      lv_str2 TYPE string VALUE 'abap'.

IF to_upper( lv_str1 ) = to_upper( lv_str2 ).
  WRITE: 'Strings are equal (case-insensitive)'.
ELSE.
  WRITE: 'Strings are different'.
ENDIF.

Converts both strings to uppercase before comparing.

4. Checking If One String is Greater/Lesser (`GT`, `LT`)

DATA: lv_str1 TYPE string VALUE 'ABAP',
      lv_str2 TYPE string VALUE 'ABAC'.

IF lv_str1 GT lv_str2.
  WRITE: 'lv_str1 is greater'.
ELSEIF lv_str1 LT lv_str2.
  WRITE: 'lv_str1 is smaller'.
ELSE.
  WRITE: 'Strings are equal'.
ENDIF.

Strings are compared lexicographically (dictionary order).

5. Using `COMPARE` Statement

DATA: lv_str1 TYPE string VALUE 'Hello',
      lv_str2 TYPE string VALUE 'hello',
      lv_result TYPE i.

COMPARE lv_str1 TO lv_str2.
lv_result = sy-subrc.

IF lv_result = 0.
  WRITE: 'Strings are equal'.
ELSE.
  WRITE: 'Strings are different'.
ENDIF.

sy-subrc = 0 → Strings are equal.
sy-subrc ≠ 0 → Strings are different.

6. Using `MATCHES` for Pattern Matching (ABAP 7.40+)

DATA: lv_str TYPE string VALUE 'Hello ABAP'.

IF lv_str MATCHES 'Hello.*'.
  WRITE: 'String starts with Hello'.
ELSE.
  WRITE: 'No match'.
ENDIF.

Useful for regular expression comparisons.

Best Practices

Use = for basic equality checks.
Use to_upper( ) for case-insensitive comparisons.
Use MATCHES for pattern-based comparisons (ABAP 7.40+).
Use GT / LT for lexical ordering.

1. Using IF for Simple Equality Comparison

2. Using IF NOT for Inequality

3. Case-Insensitive Comparison (TO UPPER CASE)

4. Checking If One String is Greater/Lesser (GT, LT)

5. Using COMPARE Statement

6. Using MATCHES for Pattern Matching (ABAP 7.40+)

Best Practices

1. Using `IF` for Simple Equality Comparison

2. Using `IF NOT` for Inequality

3. Case-Insensitive Comparison (`TO UPPER CASE`)

4. Checking If One String is Greater/Lesser (`GT`, `LT`)

5. Using `COMPARE` Statement

6. Using `MATCHES` for Pattern Matching (ABAP 7.40+)