MainframeMaster

COBOL Tutorial

COBOL END-START Statement

The END-START statement represents a fundamental component of file positioning and sequential access operations in COBOL, serving as an explicit scope terminator that clearly defines the boundaries of START statement blocks. This statement embodies modern file processing principles by providing unambiguous termination points for file positioning operations, enabling sophisticated sequential access patterns for indexed files, and supporting the development of efficient data processing applications that require precise control over file cursor positioning and record access sequences.

Basic END-START Usage

cobol
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
IDENTIFICATION DIVISION.
PROGRAM-ID. END-START-DEMO.
 
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
    SELECT EMPLOYEE-FILE ASSIGN TO 'EMPLOYEES.DAT'
        ORGANIZATION IS INDEXED
        ACCESS MODE IS DYNAMIC
        RECORD KEY IS EMP-ID
        ALTERNATE RECORD KEY IS EMP-DEPT WITH DUPLICATES
        FILE STATUS IS EMP-FILE-STATUS.
 
DATA DIVISION.
FILE SECTION.
FD  EMPLOYEE-FILE.
01  EMPLOYEE-RECORD.
    05  EMP-ID                  PIC X(10).
    05  EMP-NAME                PIC X(30).
    05  EMP-DEPT                PIC X(15).
    05  EMP-SALARY              PIC 9(7)V99.
    05  EMP-HIRE-DATE           PIC X(8).
 
WORKING-STORAGE SECTION.
01  FILE-STATUS-CONTROLS.
    05  EMP-FILE-STATUS         PIC XX.
        88  FILE-OK             VALUE '00'.
        88  RECORD-NOT-FOUND    VALUE '23'.
        88  END-OF-FILE         VALUE '10'.
        88  FILE-ERROR          VALUE '01' THRU '09', '11' THRU '22', 
                                      '24' THRU '99'.
 
01  POSITIONING-CONTROLS.
    05  START-KEY               PIC X(15).
    05  POSITION-TYPE           PIC X(10).
    05  RECORDS-READ            PIC 9(7) VALUE 0.
    05  SUCCESSFUL-STARTS       PIC 9(5) VALUE 0.
    05  FAILED-STARTS           PIC 9(5) VALUE 0.
 
PROCEDURE DIVISION.
MAIN-PROCESSING.
    PERFORM INITIALIZE-FILE-PROCESSING
    PERFORM DEMONSTRATE-BASIC-POSITIONING
    PERFORM DEMONSTRATE-RANGE-PROCESSING
    PERFORM DEMONSTRATE-ALTERNATE-KEY-POSITIONING
    PERFORM FINALIZE-FILE-PROCESSING
    STOP RUN.
 
INITIALIZE-FILE-PROCESSING.
    OPEN INPUT EMPLOYEE-FILE
    IF NOT FILE-OK
        DISPLAY 'Error opening file: ' EMP-FILE-STATUS
        STOP RUN
    END-IF.
 
DEMONSTRATE-BASIC-POSITIONING.
    DISPLAY 'Demonstrating basic file positioning...'
    
    *> Position at specific employee ID
    MOVE 'EMP005' TO EMP-ID
    START EMPLOYEE-FILE
        KEY IS EQUAL TO EMP-ID
        INVALID KEY
            DISPLAY 'Employee not found: ' EMP-ID
            ADD 1 TO FAILED-STARTS
        NOT INVALID KEY
            DISPLAY 'Positioned at employee: ' EMP-ID
            PERFORM READ-SEQUENTIAL-FROM-POSITION
            ADD 1 TO SUCCESSFUL-STARTS
    END-START.
 
READ-SEQUENTIAL-FROM-POSITION.
    PERFORM 5 TIMES
        READ EMPLOYEE-FILE NEXT RECORD
            AT END
                DISPLAY 'End of file reached'
                EXIT PERFORM
            NOT AT END
                DISPLAY 'Read: ' EMP-ID ' - ' EMP-NAME
                ADD 1 TO RECORDS-READ
        END-READ
    END-PERFORM.
 
DEMONSTRATE-RANGE-PROCESSING.
    DISPLAY 'Demonstrating range processing...'
    
    *> Position at start of range
    MOVE 'EMP010' TO EMP-ID
    START EMPLOYEE-FILE
        KEY IS GREATER THAN OR EQUAL TO EMP-ID
        INVALID KEY
            DISPLAY 'No records found >= ' EMP-ID
            ADD 1 TO FAILED-STARTS
        NOT INVALID KEY
            DISPLAY 'Positioned for range starting at: ' EMP-ID
            PERFORM PROCESS-RANGE-RECORDS
            ADD 1 TO SUCCESSFUL-STARTS
    END-START.
 
PROCESS-RANGE-RECORDS.
    PERFORM UNTIL END-OF-FILE
        READ EMPLOYEE-FILE NEXT RECORD
            AT END
                DISPLAY 'Range processing completed'
                EXIT PERFORM
            NOT AT END
                IF EMP-ID > 'EMP020'
                    DISPLAY 'End of range reached'
                    EXIT PERFORM
                END-IF
                DISPLAY 'Range record: ' EMP-ID ' - ' EMP-NAME
                ADD 1 TO RECORDS-READ
        END-READ
    END-PERFORM.
 
DEMONSTRATE-ALTERNATE-KEY-POSITIONING.
    DISPLAY 'Demonstrating alternate key positioning...'
    
    *> Position by department
    MOVE 'IT' TO EMP-DEPT
    START EMPLOYEE-FILE
        KEY IS EQUAL TO EMP-DEPT
        INVALID KEY
            DISPLAY 'Department not found: ' EMP-DEPT
            ADD 1 TO FAILED-STARTS
        NOT INVALID KEY
            DISPLAY 'Positioned at department: ' EMP-DEPT
            PERFORM READ-DEPARTMENT-RECORDS
            ADD 1 TO SUCCESSFUL-STARTS
    END-START.
 
READ-DEPARTMENT-RECORDS.
    PERFORM UNTIL END-OF-FILE
        READ EMPLOYEE-FILE NEXT RECORD
            AT END
                DISPLAY 'Department processing completed'
                EXIT PERFORM
            NOT AT END
                IF EMP-DEPT NOT = 'IT'
                    DISPLAY 'End of department reached'
                    EXIT PERFORM
                END-IF
                DISPLAY 'IT Employee: ' EMP-ID ' - ' EMP-NAME
                ADD 1 TO RECORDS-READ
        END-READ
    END-PERFORM.
 
FINALIZE-FILE-PROCESSING.
    CLOSE EMPLOYEE-FILE
    DISPLAY 'Processing Statistics:'
    DISPLAY 'Records read: ' RECORDS-READ
    DISPLAY 'Successful starts: ' SUCCESSFUL-STARTS
    DISPLAY 'Failed starts: ' FAILED-STARTS.

Best Practices and FAQ