用正则表达式。

DATA:MATCHER TYPE REF TO CL_ABAP_MATCHER.
DATA:MATCH   TYPE C LENGTH 1.

DATA:STR(10) TYPE C.

STR = '12345'.

MATCHER = CL_ABAP_MATCHER=>CREATE( PATTERN     = '\d+'
                                   TEXT        = STR ).
MATCH = MATCHER->MATCH( ).

如果MATCH = 'X'，则该字符串即为满足正则表达式的变量。