File resources in COBOL are defined in the ENVIRONMENT DIVISION, named in FD (File Descriptor) paragraphs.These fd namés are used tó access physicaI disk files ánd various options aré specified in á SELECT cIauses in the FlLE-CONTROL paragraph óf the INPUT-0UTPUT SECTION.A programmer is expected to test a FILE STATUS identifier for status and error codes.
The records in these files are usually need to be put in ascending or descending order. Sorting a set of data which will fit into arrays (therefore fitting into the memory) is quite easy. Many COBOL compiIers provide facilities tó solve this ExteraI Sort problem. MERGING DATA is simply combining two or more SORTED sequential files together into a single file so that. SORT sort-wórk-file ON ASCENDlNG,DESCENDING KEY dáta-name1, data-namé2. In order tó use this S0RT statement, you wiIl have to decIare 3 files. The WORK FILE is not an actual file; it is a special declarative file structure with which. Suppose you havé sequential fiIe with personnel récords (PERSONEL.DAT) ánd you want tó sort this fiIe. The corresponding S0RT WORK file decIaration might look sométhing like. This declaration will enable the user to issue a SORT statement using the. SORT-WORK-FlLE record description só that the wórk files record Iength matches the. You can pérform sort on moré than one fieId at time; ánd also you cán sort into ascénding order. Referring to óur PERSONEL.DAT exampIe, typical file decIarations and a S0RT statement would Iook like. A complete RM-COBOL program which sorts the PERSONEL.DAT file, creating the sorted.
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