SAP专业学习资料Intro to ABAP - Chapter 06.ppt

Mod_6 Control Statements Objectives The participants will be able to: Use the basic Control Flow Constructs that are available in the ABAP Editor Use the following statements in an ABAP Program IF, CASE, DO, WHILE, ON CHANGE OF, CHECK, EXIT, and CONTINUE Use the Logical Expressions that are available in the ABAP Editor Basic Flow Control in ABAP The IF Statement Logical Expressions Relational Operators Logical Operators Good Programming Practice withLogical Operators String Comparison Operators The CASE Statement The DO Loop The WHILE Loop Nested Loops and Control Structures The ON CHANGE OF Statement The CHECK Statement The EXIT Statement The CONTINUE Statement Summary The participants should be able to: Use the basic Control Flow Constructs that are available in the ABAP Editor Use the following statements in an ABAP Program IF, CASE, DO, WHILE, ON CHANGE OF, CHECK, EXIT, and CONTINUE Use the Logical Expressions that are available in the ABAP Editor BC170_2.06.* IF X = 5. WRITE:/ ‘The value of X is 5’. ELSEIF X = 6. WRITE:/ ‘The value of X is 6’. ELSE . WRITE:/ ‘X is neither 5 nor 6’. ENDIF. Logical Expressions use : RELATIONAL OPERATORS LOGICAL OPERATORS STRING COMPARISON OPERATORS Comparison Syntax Is Equal to =, EQ Is not equal to , , NE Greater than , GT Greater than or equal to =, = , GE Less than , LT Less than or equal to =, =, LE NOT AND OR The hierarchy of the logical operators is: NOT, AND, and then OR. (i.e., different from creating views) If not ( X = 0 ) or not ( Y = 1 and Z = X or X = 3 and ( Z = 5 ) Bad Comparison Syntax Contains only Contains any Contains string Contains pattern Contains not only Contains not any Contains no string Contains no pattern CO CA CS CP CN NA NS NP DATA: year(4) type c. …..some code to fill year variable with data….. CASE year. WHEN ‘1997’. FORMAT COLOR 6. WHEN ‘1998’. FORMAT COLOR 2. WHEN OTHERS. FORMAT COLOR 1. ENDCASE. DO. WRITE :/ ‘Hello world!’. ENDDO. J =4. DO J TIMES. WRIT