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REFERENCE NOTES FOR dBASE III version 1.1 ----------------------------------------- R E F E R E N C E - dBASE III ----------------------------- @...GET...RANGE RANGE is used in conjunction with @...GET to specify an acceptable continuous set of input values to date or numeric fields. The RANGE is initialized by specifying lower and upper bounds (inclusive) which may be literal values, memory variables, or expressions. For example: 1) Literal values: @ 10,10 GET var1 RANGE 1,9 @ 11,10 GET mdate RANGE CTOD('12/12/84'),CTOD('12/12/85') 2) Memory variables: STORE 1 TO low STORE 9 TO high @ 10,10 GET var1 RANGE low,high STORE CTOD('12/12/84') TO low_date STORE CTOD('12/12/85') TO high_date @ 10,10 GET mdate RANGE low_date,high_date 3) Expressions: @ 10,10 GET var1 RANGE low+365,high+(365*10) @ 11,10 GET mdate RANGE DATE(),high_date+120 Entries outside of the defined range will generate an error message and input will be prompted until a valid entry is made. @...GET...PICTURE Assuming a memvar is initialized with zero (that is, memvar = 0), when the user types a period at an @...GET memvar PICTURE "9999.99", dBASE will proceed to the next command line. This will not occur when the memory variable is initialized to two decimal places (that is, memvar = 0.00). Only the integer portion of the number just entered will be stored to memvar if the period is typed. @...SAY...PICTURE To display a dollar-sign character ("$") in front of a numeric value and not have the possibility of a lot of "$"s filling the blank areas, do the following: * ---To display a single "$". STORE 123.56 TO num @ 10,10 SAY "$" @ 10,11 SAY num PICTURE "99,999.99" This will generate: $ 123.56 * ---The other option available is: STORE 123.56 TO num @ 10,10 SAY num PICTURE "$$,$$$.$$" This will generate: $$$123.56 @...SAY using relative addressing We use the '$' function in dBASE II to control relative screen addressing with the @...SAY function. For example, we can have a command file print the contents of a datafile to the screen as follows: * ---This is dBASE II syntax. USE <datafile> DO WHILE .NOT. EOF * @ 5, 5 SAY <Field1> @ $+1,$ SAY <Field2> @ $+1,$ SAY <Field3> @ $+1,$ SAY <Field4> SKIP * ENDDO [while .not. eof] The dBASE III utility, dCONVERT, is used to convert dBASE II programs, datafiles, etc. to dBASE III formats. dCONVERT does not change the '$' function to ROW() and COL(); it leaves it alone. However, this will not cause any problems when executing the code in dBASE III. dBASE III will treat the '$' function as a relative addressing function. APPEND FROM <filename> [SDF/DELIMITED [WITH <delimiter>]] The DELIMITED form of the APPEND FROM command should be documented as having a WITH clause. WITH is not mentioned in the reference section. Below are a few examples: Example 1. To read a comma delimited file in which the character strings are enclosed in double quotes: APPEND FROM <filename> DELIMITED or APPEND FROM <filename> DELIMITED WITH " Example 2. To read a comma delimited file in which the character strings are enclosed in single quotes: APPEND FROM <filename> DELIMITED WITH ' Example 3. To read a comma delimited file in which the character strings are not enclosed at all: dBASE III CANNOT READ A FILE OF THIS FORMAT! Also, the syntax of the APPEND command does not include a WHILE option as the manual indicates. The correct syntax is APPEND FROM <file name> [FOR <condition>] [SDF/DELIMITED [WITH <delimiter>]] --End-- R E F E R E N C E - dBASE III ----------------------------- COPY TO <filename> [SDF/DELIMITED [WITH <delimiter>]] (1) COPY TO <filename> DELIMITED does not enclose logical fields with the specified delimiters. Numeric and date fields are also treated this way. Date fields go out in the format YYYYMMDD. (2) COPY TO <filename> DELIMITED WITH , encloses the character fields in commas and separates the fields with another comma. This command behaves differently from dBASE II as shown below: In dBASE II: . USE file1 . COPY TO file2 DELIMITED WITH , will result in: SANTA,CLAUS,NORTH POLE,ALASKA In dBASE III: . USE file1 . COPY TO file2 DELIMITED WITH , will result in: ,SANTA,,,CLAUS,,,NORTH POLE,,,ALASKA, COPY FILE <source filename> TO <target filename> The COPY FILE command copies files in 512 byte blocks; whereas, the COPY TO command will copy a .DBF file until the end-of-file. Therefore, the COPY FILE command will usually create a slightly larger file than the COPY TO command. However, the COPY FILE is faster. COPY STRUCTURE EXTENDED CREATE FROM COPY STRUCTURE EXTENDED and CREATE FROM are fully implemented in dBASE III although not documented. A brief description is given below. 1) COPY STRUCTURE EXTENDED creates a file in which the field names become the contents of one record. The syntax for this COPY option is: COPY STRUCTURE EXTENDED TO <new file> 2) CREATE FROM forms a new database (.DBF) file in which the structure is determined by the contents of a file created with COPY STRUCTURE EXTENDED. The syntax is: CREATE <new file> FROM <structure extended file> Date conversion from dBASE II The dBASE BRIDGE manual (pages 23-24) lays out an elaborate scheme for converting dBASE II "dates" to dBASE III date fields. A much easier way is to simply convert the dBASE II database file to a dBASE III file and modify the structure from character to date field. All dates stored in a dBASE II character field as "MM/DD/YY" will directly convert to a dBASE III date field. Dates that are blank CTOD() and DTOC() are intended to be inverse functions. That is, if DTOC(date) = char, then CTOD(char) = date. This is true in all circumstances except when the date is blank and the character string is " / / ". To detect a blank date, you must use the DTOC() function rather than CTOD(). For example: reg_date = CTOD("11/09/84") ? reg_date = CTOD("11/09/84") .T. ? DTOC(reg_date) = "11/09/84" .T. * ---With a blank date the following occurs: blank_date = CTOD(" / / ") ? blank_date = CTOD(" / / ") .F. ? DTOC(blank_date) = " / / " .T. As is evident from the example, the blank date is handled differently than the non-blank date. DISPLAY and LIST The DISPLAY and LIST commands are documented in the manual as not having a FIELDS clause as part of the syntax, while the ASSIST and HELP menu options assume the FIELDS clause is required. dBASE III will accept either syntax for these two commands. FILE() function The FILE() function only searches the current directory. SET PATH TO does not affect this function. If other directories are to be searched, they must be supplied to the function. For example, * ---This will not find Data.dbf, if Data.dbf is in the * ---subdirectory ACCTS. SET PATH TO \DBASE\ACCTS IF FILE( "DATA.DBF" ) DO Process ENDIF Workaround: * ---This method will work. mpath = "\DBASE\ACCTS\" SET PATH TO &mpath IF FILE( mpath + "DATA.DBF" ) DO Process ENDIF --End-- R E F E R E N C E - dBASE III ----------------------------- FIND SEEK FIND and SEEK are both used to move the record pointer of an indexed database to the first instance of the index key that matches the search argument. FIND searches on a literal character string while SEEK searches on an expression the value of which may be character, date, or numeric. The proper choice of command is related to the context and data type of the index key. Generally, FIND will only be used to search for a literal character string and SEEK for all other searches. The following are some typical cases: (1) You have an index key that is character and are working from the dot prompt: . FIND Lee {or} . SEEK "Lee" (2) You have an index key that is numeric or date and are working from the dot prompt: . SEEK 1250 . SEEK CTOD('12/12/85') (3) You are working within a command file and are initializing a memory variable as a search key: STORE SPACE(10) TO skey @ 10,10 SAY 'Enter value to search for' GET skey READ SEEK skey (4) You have a database field that is character, Code, and the contents are numeric digits and right-justified: ACCEPT 'Enter code to search for' to skey SEEK SPACE(LEN(Code) - LEN(skey)) + skey (5) You are working with several databases and want to search for a key value in the current work area using a field variable from a non-active area with an alias name: SELECT 1 USE File1 INDEX File1 SELECT 2 USE File2 INDEX File2 SELECT File1 SEEK File2->Field1 Function Keys F1 toggles the cursor control menu on and off in the following full screen edit modes. APPEND EDIT MODIFY LABEL MODIFY STRUCTURE BROWSE CHANGE MODITY REPORT INPUT The INPUT command does not initialize a memory variable of any type if <RETURN> is pressed at its prompt. The dBASE III manual says this will produce a syntax error (page 4-58). What really happens is that a syntax error will result if the non-existent memvar is later referenced. MEMO fields (1) MEMO fields are used to contain up to 5,000 characters of text information that is to be associated with a database record. Information may be read into a MEMO field using Ctrl-K-R and written to text files using Ctrl-K-W. Information from MEMO fields can be displayed or printed by using LIST, DISPLAY, ?. The field must be specified with these commands. However, these commands cause the MEMO field to wrap at 50 columns. The REPORT FORM may be used to output MEMO fields with line widths of more or less than 50 characters. (2) PACKing a database file with memo fields will not decrease the amount of disk space used by the .DBT file. The command file below demonstrates how to remove the deleted records and free the unused disk space. SET DELETED ON USE Filea COPY TO Temp CLOSE DATABASE ERASE Filea.dbf ERASE Filea.dbt RENAME Temp.dbf TO Filea.dbf RENAME Temp.dbt TO Filea.dbt SET DELETED OFF MODIFY STRUCTURE In MODIFY STRUCTURE, Ctrl-Home will bring up a menu on line 0 with the four choices listed below. Bottom Top Field # Menu They are selected with cursor control keys and <RETURN>. Bottom moves the cursor to the last field, Top to the first. Field # allows selection of a field number, then moves the cursor to it. Menu toggles the cursor control menu off and on. This feature is not documented under MODIFY STRUCTURE. MODIFY STRUCTURE The "Warning" in the documentation on page 4-73 of dBASE III version 1.00 and WARNING of page 4-80 of dBASE III version 1.10 should read as follows: WARNING: Although you may change field names and field lengths, if you change both at once, the data of the fields that have been modified will not be appended into the new structure. Note that in the ASSIST mode, the following screen message is not entirely true, "Information in the database file is preserved where field names remain the same." As noted above, if only field names are changed or only the length, the data is appended into the new structure. The correct procedure when both field name(s) and field length(s) need to be changed, is to modify the field name(s) first, and then re-enter MODIFY STRUCTURE and modify the field length(s). Also, note that deleting a field (with Ctrl-U) has the same effect as modifying the field length. Therefore, make deletions at the same time you make field length changes. --End-- R E F E R E N C E - dBASE III ----------------------------- Numeric fields with decimal places Although not documented, dBASE III expects the user to allow for a leading digit and a decimal point on numeric fields containing decimal places. For example, a numeric field of two decimal places should not be defined any smaller than four digits in length--one position for the leading digit, one position for the decimal point, and two positions for the two decimal places. If the structure for a numeric field does not allow for a leading digit (such as, a width of three and two decimal places), numeric input to the numeric field will always be stored as zero. Also, if other numeric fields follow this field, they might automatically be zeroed out when numeric data is entered to the first field. Numeric input of large numbers If a variable is initialized to zero, dBASE III does not allow input larger than 10 digits when using the @...GET command, even if the PICTURE clause is used. For example: x = 0 @ 5,5 SAY "Enter digits" GET x PICTURE "99999999999" (There are eleven 9's) ----------^ READ The display is: Enter digits 0 If an eleven digit value is entered, the display is: Enter digits ********** (10 asterisks) This can be avoided by initializing 'x' to a value greater than ten digits (such as, 1000000000). This problem does not occur if a field is used rather than a memory variable. PARAMETERS, passing Fields (For a manual update, see the TechNotes "Policies" section.) In the documentation concerning PARAMETERS when used in conjunction with the DO <filename> [WITH <parameter list>] command, page 4-76 of the version 1.0 manual states, "A passed parameter may be any legitimate expression." Also, in the Glossary (page 7-3) the definition for Expression is, "Expression may consist of a field, a memory variable, a function, a constant, or any combination thereof." However, when a DO is invoked with a field in the parameter list, dBASE III will give the message, "Variable not found." In order to use a field name in the parameter list, you must use the Alias -> Fieldname form. For example: USE Filea DO <Filename> WITH Filea -> Field1 will work, but the following will not. USE Filea DO <Filename> WITH Field1 --End-- R E F E R E N C E - dBASE III ----------------------------- PRIVATE In dBASE III, all variables are PRIVATE to the routine in which they are initialized unless otherwise declared. Variables created at the dot prompt will automatically be PUBLIC no matter how they are declared. Declaring a variable PRIVATE in a command file hides any outer- level definition of a variable with the same name from the current routine. It also hides any deeper-level routines from viewing any outer-level definition of a variable with the same name. In the example below, programs B.PRG and C.PRG do not have access to variable X in program A.PRG. Program C.PRG, therefore, will display X with a value of 15 and not 10. Program A.PRG, however, will display X with the old value of 10 even after executing program B.PRG. * A.PRG x = 10 DO B ----------> * B.PRG ? x PRIVATE x RETURN x = 15 DO C ----------> * C.PRG RETURN ? x RETURN In programming, you will want to declare a variable PRIVATE in a subroutine if you do not want this variable to interfere with an outer-level variable having the same name. To illustrate the use of PRIVATE, the command files MAIN.PRG and SUB.PRG are listed below, with the displayed output. Notice that all the variables are released when MAIN.PRG returns control to the dot prompt. Also notice that the variables initialized in MAIN.PRG are PRIVATE in the memory display even though they are never explicitly declared. Lastly, notice that the value assigned to height in SUB.PRG is not returned to MAIN.PRG, but the value assigned to area in SUB.PRG is returned. This is because height is declared PRIVATE in SUB.PRG and area is not. LISTINGS: * MAIN.PRG * -------- area = 0 height = 304 ? "Before call to SUB:" ? "-------------------" DISPLAY MEMORY DO Sub ------------------> * SUB.PRG ? "After call to SUB:" * ------- ? "------------------" PRIVATE height DISPLAY MEMORY height = 30 RETURN area = 10 * 20 * height * EOF: MAIN.PRG ? "Inside SUB:" ? "-----------" DISPLAY MEMORY RETURN * EOF: SUB.PRG OUTPUT: Before call to SUB: ------------------- AREA priv N 0 ( 0.00000000) HEIGHT priv N 304 ( 304.00000000) 2 variables defined, 18 bytes used 254 variables available, 5982 bytes available Inside SUB: ----------- AREA priv N 6000 ( 6000.00000000) HEIGHT priv (hidden) N 304 ( 304.00000000) HEIGHT priv N 30 ( 30.00000000) 3 variables defined, 27 bytes used 253 variables available, 5973 bytes available After call to SUB: ------------------ AREA priv N 6000 ( 6000.00000000) HEIGHT priv N 304 ( 304.00000000) 2 variables defined, 18 bytes used 254 variables available, 5982 bytes available When DISPLAY MEMORY is entered from the dot prompt the following two lines will display: 0 variables defined, 0 bytes used 256 variables available, 6000 bytes available >>> PROCEDURE Calling Command Files from Procedures within dBASE III ------------------------------------------------------ To call a command file from a procedure, you must follow a few rules. Rule 1: The command file cannot have the same name as any of the procedures in the file even if the extension is included as part of the filename. An attempt to do this will cause the inappropriate error message, "Unrecognized phrase/keyword in command." For example: * Proc_One.PRG PROCEDURE One * ---The next command will not work because * ---Two is a procedure in this file. DO Two.PRG RETURN * PROCEDURE Two * ---The next command will work. DO Three.PRG RETURN * EOF: Proc_One.PRG This can be avoided by renaming either the command file or procedure. To avoid this problem you might want to begin procedure names with a prefix that command files will not have. For instance, in the previous example the procedures could have been called P_One and P_Two. Rule 2: Once the command file is invoked from a procedure file, it must not DO another procedure in the procedure file. Instead, it should RETURN to the calling procedure. Otherwise, the called procedure will usually execute, but an error message will be displayed for a command line that does not exist. Rule 3: Internal procedure calls (that is, a procedure that calls either itself or another procedure in the same file) must be kept to eighteen nested calls or less. The nineteenth call attempt will return execution to the calling command file with no error message. PUBLIC PUBLIC is used to declare memory variables as global and to prevent their release when control is returned to the dot prompt. PUBLIC variables must be declared prior to being initialized, and once declared, these variables will be assigned a logical false value until initialized. PUBLIC variables can be re-declared as PUBLIC without losing the values already stored in them. In programming, declaring all variables as PUBLIC in the main routine would make dBASE III behave similar to dBASE II. However, there is one difference in dBASE III, PUBLIC variables can only be released by the CLEAR MEMORY, CLEAR ALL, and RELEASE <variable list> commands, but not the RELEASE ALL command. RELEASE ALL CLEAR MEMORY RELEASE ALL and CLEAR MEMORY are not equivalent commands as the dBASE III manual states. CLEAR MEMORY clears all memory variables, regardless where they were initialized. RELEASE ALL, however, will release all memory variables except those declared PUBLIC or initialized in a nested command file. REPLACE REPLACE ALL does not replace all records correctly if an index is in use and the key field is replaced. Only the first record and those that logically follow the new value will be replaced. This occurs because the index is automatically updated (in-place key updating) when it is edited. The record pointer moves to the record following the new position, not to the record following the old position. This can be illustrated in the example given below (the data file has five records with the field CHARS-C-1, and is indexed on this field): . LIST Record# CHARS 1 a 2 b 3 c 4 i 5 j . REPLACE ALL Chars WITH 'd' 3 records replaced . LIST 2 b 3 c 1 d 4 d 5 d The manual warns against block replacements to the key field. The correct procedure would be to REPLACE with no indexes in use, open the indexes with SET INDEX TO, and then REINDEX. REPORT FORM MODIFY REPORT (1) The report generator will right-justify field headings for numeric fields when the report is run. (2) If the PLAIN clause is specified with REPORT FORM TO PRINT, no page ejects occur. The report prints through to the end without page breaks. (3) MODIFY REPORT will allow the number of decimal places to be changed from the default. If this is done and the report is run, everything is as expected. However, if the report is modified again, the number of decimal places reverts to the default when the cursor reaches the "# decimal places" field. (4) Although not documented in the manual or in the cursor control menu, Ctrl-N inserts a column in a report being created or modified. However, its counterpart (Ctrl-U which deletes a column) is documented and included in the help menu. --End-- R E F E R E N C E - dBASE III ----------------------------- Reserved words Page 1-138 of the tutorial in the first edition f te mnua uses a sample routine which creates a memory vrible ith he name 'continue.' Since this is a reserved wod, BAE II wil give the message, "No database in USE, enter filenam." dBASE III is assuming you intend to CONTINUE on a LOCATE command. This will only happen if you use the <variable> = <value> form of assignment; dBASE III will execute correctly when you use the STORE <value> TO <variable> form. Other words that will not work with the first syntax are: AVERAGE, COUNT, and SUM. ROW() COL() After a READ, the ROW() function always returns 24; however, the COL() function does not change. For example: SET TALK OFF var = SPACE(2) @ 5,40 GET var ? ROW(), COL() <--- This returns 6 and 3. READ ? ROW(), COL() <--- This returns 24 and 3. RUN (or !) The RUN command requires that COMMAND.COM be in the boot drive or the directory indicated by SET COMSPEC. Otherwise, the incorrect error message "Insufficient memory" is displayed. RUN COMMAND You can get the equivalent to Framework's DOS Access in dBASE III by issuing RUN COMMAND. This will leave you at the DOS operating system level, and will allow you to enter any DOS commands. To get back to the dBASE III dot prompt, type EXIT. SET ALTERNATE TO dBASE III will not send a linefeed (that is, CHR(10)) to an alternate file (Word Perfect looks for this linefeed character in its mail merge program). The following command file: SET ALTERNATE TO x SET ALTERNATE ON ?? "first LF" ?? CHR(10) ?? "second LF" SET ALTERNATE OFF CLOSE ALTERNATE will generate the following test file: first LFsecond LF As you can see, there is no linefeed in the file. SET CONSOLE ON/OFF The SET CONSOLE ON/OFF command behaves differently in dBASE III than it does in dBASE II. Specifically, it has no effect when issued at the dot prompt, and if SET CONSOLE OFF is issued in a command file that neglects to SET CONSOLE ON, dBASE III will automatically set the console back on upon the termination of execution of that file. This includes normal termination as well as termination by means of pressing the escape key. SET MENUS ON/OFF The default for SET MENUS is OFF. However, ASSIST leaves MENUS SET ON even if they were off prior to entering ASSIST. SET PROCEDURE TO PARAMETERS, PROCEDURE The following program and procedure files illustrate the use of parameter passing with procedures. FUTVALUE.PRG calculates the future value of an investment and the future value of an annuity with the use of the BUSINESS.PRG procedure file. Notice how the parameters can be passed to BUSINESS.PRG. They can either be literal numbers, expressions, or variables. Also, notice that the PARAMETERS command is included after each PROCEDURE that receives parameters. LISTINGS: * FUTVALUE.PRG * ------------ SET TALK OFF SET FIXED ON SET PROCEDURE TO Business * * { Calculate future value of an investment } result = 0.00 DO FV WITH 6000.00, 8.5, 4, 5, result ? result * * { Calculate future value of regular deposits (Annuity) } result = 0.00 DO FVA WITH 150.00, 7.0, 12, 2, result ? result * CLOSE PROCEDURE SET FIXED OFF SET TALK ON RETURN * EOF: FUTVALUE.PRG * BUSINESS.PRG { Library of business procedures } * ------------ * PROCEDURE FV { Calculate future value of an investment } PARAMETERS amount, rate, periods, years, result rate = rate / periods / 100 result = amount * (1 + rate) ^ (periods * years) result = ROUND( result, 2 ) RETURN * PROCEDURE FVA { Calculate future value of regular deposits } PARAMETERS amount, rate, periods, years, result rate = rate / periods / 100 result = amount * ( (1 + rate) ^ (periods *; years) - 1 ) / rate result = ROUND( result, 2 ) RETURN * * EOF: BUSINESS.PRG OUTPUT: 9136.77 3852.15 --End-- INDEX OF TOPICS R E F E R E N C E - dBASE III Select Topic ------ --------------------------------------- 1. @...GET...RANGE @...GET...PICTURE @...SAY...PICTURE @...SAY using relative addressing APPEND FROM [SDF/DELIMITED [WITH <delimiter>]] 2. COPY TO <filename> [SDF/DELIMITED [WITH <delimiter>]] COPY FILE <source filename> TO <target filename> COPY STRUCTURE EXTENDED CREATE FROM Date conversion from dBASE II Dates that are blank DISPLAY and LIST FILE() function 3. FIND SEEK Function Keys INPUT MEMO fields MODIFY STRUCTURE 4. Numeric fields with decimal places Numeric input of large numbers PARAMETERS, passing fields 5. PRIVATE PROCEDURE - Calling Command Files from Procedures PUBLIC RELEASE ALL CLEAR MEMORY REPLACE REPORT FORM MODIFY REPORT 6. Reserved words ROW() COL() RUN (or !) RUN COMMAND.COM SET ALTERNATE TO SET CONSOLE ON/OFF SET MENUS ON/OFF SET PROCEDURE TO PARAMETERS, PROCEDURE 7. SET RELATION TO <expression> INTO <alias> SET UNIQUE ON/OFF Warning against using a dBASE III file with dBASE II --End--