HP OpenVMS Systems

The COMP% function compares two numeric strings and returns -1, 0, or 1, depending on the results of the comparison.

Format

Syntax Rules

Str-exp1 and str-exp2 are numeric strings with an optional minus sign (-), ASCII digits, and an optional decimal point (.).

Remarks

1. If str-exp1 is greater than str-exp2, COMP% returns 1.
2. If the string expressions are equal, COMP% returns 0.
3. If str-exp1 is less than str-exp2, COMP% returns -1.
4. The value returned by the COMP% function is an integer of the default size.
5. The COMP% function does not support E-format notation.

Example

DECLARE STRING num_string, old_num_string, &
        INTEGER result
num_string = "-24.5"
old_num_string = "33"
result = COMP%(num_string, old_num_string)
PRINT "The value is ";result

Output

The value is -1

The CONTINUE statement causes BASIC to clear an error condition and resume execution at the statement following the statement that caused the error or at the specified target.

Format

Syntax Rules

If you specify a target, it must be a label or line number that appears either inside the associated protected region, inside a WHEN block protected region that surrounds the current protected region, or in an unprotected region of code.

Remarks

1. CONTINUE with no target causes BASIC to transfer control to the statement immediately following the statement that caused the error. The next remark is an exception to this rule.
2. If an error occurs on a FOR, NEXT, WHILE, UNTIL, SELECT or CASE statement, control is transferred to the statement immediately following the corresponding NEXT or END SELECT statement, as in the following code:

   10 WHEN ERROR IN A=10 B=1 20 FOR I=A TO B STEP 2 30 GET #1 40 C=1 NEXT I 50 C=0 USE . . . CONTINUE END WHEN

   
   If an error occurs on line 20, the CONTINUE statement transfers control to line 50. If an error occurs on line 30, program control resumes at line 40.
3. The CONTINUE statement must be lexically inside of a handler.
4. If you specify a CONTINUE statement within a detached handler, you cannot specify a target.

Example

WHEN ERROR USE err_handler
   .
   .
   .
END WHEN
   .
   .
   .
HANDLER err_handler
     SELECT ERR
         CASE = 50
              PRINT "Insufficient data"
              CONTINUE
         CASE ELSE
         EXIT HANDLER
     END SELECT
END HANDLER

The COS function returns the cosine of an angle in radians or degrees.

Format

Syntax Rules

None

Remarks

1. The returned value is from -1 to 1. The parameter value is expressed in either radians or degrees depending on which angle clause you choose with the OPTION statement.
2. BASIC expects the argument of the COS function to be a real expression. When the argument is a real expression, BASIC returns a value of the same floating-point size. When the argument is not a real expression, BASIC converts the argument to the default floating-point size and returns a value of the default floating-point size.

Example

DECLARE SINGLE cos_value
cos_value = 26
PRINT COS(cos_value)

Output

 .646919

The CTRLC function enables Ctrl/C trapping. When Ctrl/C trapping is enabled, a Ctrl/C typed at the terminal causes control to be transferred to the error handler currently in effect.

Format

Syntax Rules

None

Remarks

1. When BASIC encounters a Ctrl/C, control passes to the error handler currently in effect. If there is no error handler in a program, the program aborts.
2. In a series of linked subprograms, setting Ctrl/C for one subprogram enables Ctrl/C trapping for all subprograms.
3. When you trap a Ctrl/C with an error handler, your program may be in an inconsistent state; therefore, you should handle the Ctrl/C error and exit the program as quickly as possible.
4. Ctrl/C trapping is asynchronous; that is, BASIC suspends execution and signals "Programmable ^C trap" (ERR=28) as soon as it detects a Ctrl/C. Consequently, a statement can be interrupted while it is executing. A statement so interrupted may be only partially executed and variables may be left in an undefined state.
5. BASIC can trap more than one Ctrl/C error in a program as long as the error does not occur while the error handler is executing. If a second Ctrl/C is detected while the error handler is processing the first Ctrl/C, the program aborts.
6. The CTRLC function always returns a value of zero.
7. The function RCTRLC disables Ctrl/C trapping. See the description of the RCTRLC function for further details.

Example

WHEN ERROR USE repair_work
Y% = CTRLC
   .
   .
   .
END WHEN
HANDLER repair_work
IF (ERR=28) THEN PRINT "Interrupted by CTRLC!"
   .
   .
   .
END HANDLER

The CVT$$ function is a synonym for the EDIT$ function. See the EDIT$ function for more information.

Format

The CVT$% function maps the first two characters of a string into a 16-bit integer. The CVT%$ function translates a 16-bit integer into a 2-character string. The CVT$F function maps a 4- or 8-character string into a floating-point variable. The CVTF$ function translates a floating-point number into a 4- or 8-byte character string. The number of characters translated depends on whether the floating-point variable is single- or double-precision.

Format

Syntax Rules

CVT functions reverse the order of the bytes when moving them to or from a string. Therefore, you can mix MAP and MOVE statements, but you cannot use FIELD and CVT functions on a file if you also plan to use MAP or MOVE statements.

Remarks

1. CVT$%
   • If the CVT$% str-var has fewer than two characters, BASIC pads the string with nulls.
   • If the default data type is LONG, only 2 bytes of data are extracted from str-var; the high-order byte is sign-extended into a longword.
   • The value returned by the CVT$% function is an integer of the default size.
2. CVT%$
   • Only 2 bytes of data are inserted into str-var.
   • If you specify a floating-point variable for int-var, BASIC truncates it to an integer of the default size. If the default size is BYTE and the value of int-var exceeds 127, BASIC signals an error.
3. CVT$F
   • CVT$F maps four characters when the program is compiled with /SINGLE and eight characters when the program is compiled with /DOUBLE.
   • If str-var has fewer than four or eight characters, BASIC pads the string with nulls.
   • The real-var returned by the CVT$F function is the default floating-point size. If the default size is not SINGLE or DOUBLE, BASIC signals the error "Floating CVT valid only for SINGLE or DOUBLE."
4. CVTF$
   • The CVTF$ function maps single-precision numbers to a 4-character string and double-precision numbers to an 8-character string.
   • BASIC expects the argument of the CVTF$ function to be a real expression. When the argument is a real expression, BASIC returns a value of the same floating-point size. When the argument is not a real expression, BASIC converts the argument to the default floating-point size and returns a value of the default floating-point size. If the default floating-point size is not SINGLE or DOUBLE, BASIC signals the error "Floating CVT valid only for SINGLE or DOUBLE."

Examples

Example 1

DECLARE STRING test_string, another_string
DECLARE LONG first_number, next_number
test_string = "AT"
PRINT CVT$%(test_string)
another_string = "at"
PRINT CVT$%(another_string)
first_number = 16724
PRINT CVT%$(first_number)
next_number = 24948
PRINT CVT%$(next_number)
END

Output

 16724
 24948
AT
at

Example 2

DECLARE STRING test_string, another_string
DECLARE SINGLE first_num, second_num
test_string = "DESK"
first_num = CVT$F(test_string)
PRINT first_num
another_string = "desk"
second_num = CVT$F(another_string)
PRINT second_num
PRINT CVTF$(first_num)
PRINT CVTF$(second_num)
END

$ BASIC/SINGLE CVTF
$ LINK CVTF
$ RUN CVTF

Output

 .218256E+12
 .466242E+31
DESK
desk

The DATA statement creates a data block for the READ statement.

Format

Syntax Rules

1. Num-lit specifies a numeric literal.
2. Str-lit is a character string that starts and ends with double or single quotation marks. The quotation marks must match.
3. Unq-str is a character sequence that does not start or end with double quotation marks and does not contain a comma.
4. Commas separate data elements. If a comma is part of a data item, the entire item must be enclosed in quotation marks.

Remarks

1. Because BASIC treats comment fields in DATA statements as part of the DATA sequence, you should not include comments.
2. A DATA statement must be the last or the only statement on a physical line.
3. DATA statements must end with a line terminator.
4. When a DATA statement is continued with an ampersand (&), BASIC interprets all characters between the keyword DATA and the ampersand as part of the data. Any code that appears on a noncontinued line is considered a new statement.
5. You cannot use the percent sign suffix for integer constants that appear in DATA statements. An attempt to do so causes BASIC to signal the error, "Data format error" (ERR=50).
6. DATA statements are local to a program module.
7. BASIC does not execute DATA statements. Instead, control is passed to the next executable statement.
8. A program can have more than one DATA statement. BASIC assembles data from all DATA statements in a single program unit into a lexically ordered single data block.
9. BASIC ignores leading and trailing blanks and tabs unless they are in a string literal.
10. Commas are the only valid data delimiters. You must use a quoted string literal if a comma is to be part of a string.
11. BASIC ignores DATA statements without an accompanying READ statement.
12. BASIC signals the error "Data format error" if the DATA item does not match the data type of the variable specified in the READ statement or if a data element that is to be read into an integer variable ends with a percent sign (%). If a string data element ends with a dollar sign ($), BASIC treats the dollar sign as part of the string.

Example

10 DECLARE INTEGER A,B,C
   READ A,B,C
   DATA 1,2,3
   PRINT A + B + C

Output

 6

The DATE$ function returns a string containing a day, month, and year in the form dd-mmm-yy.

Format

Syntax Rules

1. Int-exp can have up to 6 digits in the form yyyddd, where the characters yyy specify the number of years since 1970 and the characters ddd specify the day of that year. The day of year must be a value between 1 and the number of days in the specified year.
2. You must fill all three of the d positions with digits or zeros before you can fill the y positions. For example:
   • DATE$(121) returns the date 01--May--70, day 121 of the year 1970.
   • DATE$(1201) returns the date 20--Jul--71, day 201 of the year 1971.
   • DATE$(12001) returns the date 01--Jan--82, day one of the year 1982.
   • DATE$(10202) returns the date 20--Jul--80, day 202 of the year 1980.

Remarks

1. If int-exp equals zero, DATE$ returns the current date.
2. The str-var returned by the DATE$ function consists of nine characters and expresses the day, month, and year in the form dd-mmm-yy.
3. If you specify an invalid date, such as day 385, results are unpredictable.
4. If you specify a floating-point expression for int-exp, BASIC truncates it to an integer of the default size.

Example

DECLARE STRING todays_date
todays_date = DATE$(0)
PRINT todays_date

Output

09-Oct-99

The DATE4$ function is strongly recommended as replacement for the DATE$ function to avoid problems in the year 2000 and beyond. It functions the same as the DATE$ function except that the year portion of the result string contains two more digits indicating the century. For example:

PRINT 32150, DATE$ (32150), DATE4$ (32150)

This produces the following output:

32150   30-May-02   30-May-2002

The DATE4$ function returns a string containing a day, month, and year in the form dd-mmm-yyyy.

Format

Syntax Rules

1. Int-exp can have up to 6 digits in the form yyyddd, where the characters yyy specify the number of years since 1970 and the characters ddd specify the day of that year. The day of year must be a value between 1 and the number of days in the specified year.
2. You must fill all three of the d positions with digits or zeros before you can fill the y positions.

Remarks

The DATE4$ function is strongly recommended as replacement for the DATE$ function to avoid problems in the year 2000 and beyond. It functions the same as the DATE$ function except that the year portion of the result string contains two more digits indicating the century. For example:

PRINT 32150, DATE$ (32150), DATE4$ (32150)

Produces the following output:

32150   30-May-02   30-May-2002

See the description of the DATE$ function for more information.

The DECIMAL function converts a numeric expression or numeric string to the DECIMAL data type.

Format

Syntax Rules

1. Int-const1 specifies the total number of digits (the precision) and int-const2 specifies the number of digits to the right of the decimal point (the scale). If you do not specify these values, BASIC uses the d (digits) and s (scale) defaults for the DECIMAL data type.
2. Int-const1 and int-const2 must be positive integers from 1 to 31. Int-const2 cannot exceed the value of int-const1.
3. Exp can be either numeric or numeric string. If a numeric string, it can contain the ASCII digits 0 to 9, a plus sign (+), a minus sign (-), and a period (.).

Remarks

1. If exp is a string, BASIC ignores leading and trailing spaces and tabs.
2. The DECIMAL function returns a zero when a string argument contains only spaces and tabs, or when it is null.

Example

DECLARE STRING CONSTANT format_string = "##.###"
DECLARE STRING num_value, DECIMAL(5,3) B
INPUT "Enter a numeric value";num_value
B = DECIMAL(num_value,5,3)
PRINT USING format_string, B

Output

Enter a numeric value? 6
 6.000

The DECLARE statement explicitly assigns a name and a data type to a variable, an entire array, a function, or a constant.

Format

Syntax Rules

1. Data-type can be any BASIC data type keyword or a data type defined by a RECORD statement. Data type keywords, size, range, and precision are listed in Table 1-2.
2. Variables
   • Decl-item names an array, a record, or a variable.
   • A decl-item named in a DECLARE statement cannot be named in another DECLARE statement, or in a DEF, EXTERNAL, FUNCTION, SUB, COMMON, MAP, DIM, HANDLER, or PICTURE statement.
   • Each decl-item is associated with the preceding data type. A data type is required for the first decl-item.
   • Decl-items of data type STRING are dynamic strings.
   • When you declare an array, BASIC allows you to specify both lower and upper bounds for each dimension of the array. The upper bound is required; the lower bound is optional.
     • Int-const1 specifies the lower bounds of the array.
     • Int-const2 specifies the upper bounds of the array and, when accompanied by int-const1, must be preceded by the keyword TO.
     • Int-const1 must be less than or equal to int-const2.
     • If you do not specify int-const1, BASIC uses zero as the default lower bound.
     • Int-const1 and int-const2 can be any combination of negative or positive values or zero.
3. DEF Functions
   • Def-name names the DEF function.
   • Data-type specifies the data type of the value the function returns.
   • Def-params specify the number and, optionally, the data type of the DEF parameters. Parameters define the arguments the DEF expects to receive when invoked.
     • When you specify a data type, all following parameters are of that data type until you specify a new data type.
     • If you do not specify any data type, parameters take the current default data type and size.
     • The number of parameters equals the number of commas plus 1. For example, empty parentheses specify one parameter of the default type and size; one comma inside the parentheses specifies two parameters of the default type and size; and so on. One data type inside the parentheses specifies one parameter of the specified data type; two data types separated by one comma specifies two parameters of the specified type, and so on.
4. Named Constants
   • Const-name is the name you assign to the constant.
   • Data-type specifies the data type of the constant. The value of the const must be numeric if the data type is numeric and string if the data type is STRING. If the data type is STRING, const must be a quoted string or another string constant.
   • Const-exp cannot be a data type that was defined with the RECORD statement.
   • Data-type cannot be a data type defined by a record statment.
   • String constants cannot exceed 498 characters.
   • BASIC allows const-exp to be an expression for all data types except DECIMAL. Expressions are not allowed as values when you name DECIMAL constants.
   • Allowable operators in DECLARE CONSTANT expressions include all valid arithmetic, relational, and logical operators except exponentiation. Built-in functions cannot be used in DECLARE CONSTANT expressions. The following examples use valid expressions as values:

     DECLARE DOUBLE CONSTANT max_value = (PI/2) DECLARE STRING CONSTANT left_arrow = "<-----" + LF + CR

Remarks

1. The DECLARE statement is not executable.
2. The DECLARE statement must lexically precede any reference to the variables, functions, or constants named in it.
3. To declare a virtual or run-time array, use the DIMENSION statement.
4. Variables
   • Subsequent decl-items are associated with the specified data type until you specify another data type.
   • All variables named in a DECLARE statement are initialized to zero if numeric or to the null string if string.
5. DEF Functions
   • The DECLARE FUNCTION statement allows you to name a function defined in a DEF or DEF* statement, specify the data type of the value the function returns, and declare the number and data type of the parameters.
   • Data type keywords must be separated by commas.
   • The first specification of a data type for a def-param is the default for subsequent arguments until you specify another def-param. For example:

     DECLARE DOUBLE FUNCTION interest(DOUBLE,SINGLE,,)

     
     This example declares two parameters of the default type and size, one DOUBLE parameter, and three SINGLE parameters for the function named interest.
6. Named Constants
   • The DECLARE CONSTANT statement allows you to name a constant value and assign a data type to that value. Note that you can specify only one data type in a DECLARE CONSTANT statement. To declare a constant of another data type, you must use a second DECLARE CONSTANT statement.
   • During program execution, you cannot change the value assigned to the constant.
   • The specified data-type determines the data type of the constant. For example:

     DECLARE LONG CONSTANT True = -1, False = 0 DECLARE REAL CONSTANT ZZZ = 123.0 DECLARE BYTE CONSTANT YYY = '123'L PRINT True, False, ZZZ, YYY

     
     Output

     ---

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