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<!doctype html public>
<html>
<title>Xbase DBMS Chapter 16</title>
<body bgcolor=#FFFFFF>
<h1><p align="center">Expressions Reference<br></h1>
<p align="center">Chapter Updated 2/19/04</p><hr>
<br><br>
<table border>
<caption align=top><h3>Expression Operands</h3></caption>
<TR VALIGN="BASELINE">
<TR><TH ALIGN="LEFT">Operand<TD>Type<TD>Function
<TR><TH ALIGN="LEFT">+<TD>Alpha<TD>Concatonate
<TR><TH ALIGN="LEFT">+<TD>Numeric<TD>Addition
<TR><TH ALIGN="LEFT">-<TD>Alpha<TD>Concatonate, remove white space
<TR><TH ALIGN="LEFT">-<TD>Numeric<TD>Subtraction
<TR><TH ALIGN="LEFT">*<TD>Numeric<TD>Multiplication
<TR><TH ALIGN="LEFT">/<TD>Numeric<TD>Division
<TR><TH ALIGN="LEFT">**<TD>Numeric<TD>Exponentiation
<TR><TH ALIGN="LEFT"><<TD>Logical<TD>Less Than
<TR><TH ALIGN="LEFT">><TD>Logical<TD>Greater Than
<TR><TH ALIGN="LEFT">=<TD>Logical<TD>Equal
<TR><TH ALIGN="LEFT"><><TD>Logical<TD>Not Equal
<TR><TH ALIGN="LEFT">#<TD>Logical<TD>Not Equal
<TR><TH ALIGN="LEFT"><=<TD>Logical<TD>Less Than or Equal
<TR><TH ALIGN="LEFT">>=<TD>Logical<TD>Greater Than or Equal
<TR><TH ALIGN="LEFT">$<TD>Logical<TD>Contains
<TR><TH ALIGN="LEFT">-><TD>N/A<TD>Identifies database field ie; DATABASE->FIELD
<TR><TH ALIGN="LEFT">.AND.<TD>Logical<TD>Logical AND
<TR><TH ALIGN="LEFT">.OR.<TD>Logical<TD>Logical OR
</TABLE>
<br><br><br>
<TABLE BORDER>
<CAPTION ALIGN="TOP"><h3>Expression Functions</h3></CAPTION>
<TR VALIGN="BASELINE">
<TR><TH ALIGN="LEFT">Expression Function<TD>Xbase C++ Method<TD>Description
<TR><TH ALIGN="LEFT">ABS()<TD>xbDouble EXPN::ABS( xbDouble d )<TD>
Returns absolute numeric value of argument.
<TR><TH ALIGN="LEFT">ASC()<TD>xbLong EXPN::ASC( char * String )<TD>
Returns ASCII code of left character of string.
<TR><TH ALIGN="LEFT">AT()<TD>xbLong EXPN::AT( char *s1, char *s2 )<TD>
Returns starting position of first alphanumeric argument in second argument.
<TR><TH ALIGN="LEFT">CDOW()<TD>char * EXPN::CDOW( char Date8 )<TD>
Returns name of the day of the week of Date8.
<TR><TH ALIGN="LEFT">CHR()<TD>char * EXPN::CHR( xbLong l )<TD>
Returns ASCII character corresponding to numeric value supplied.
<TR><TH ALIGN="LEFT">CMONTH()<TD>char * EXPN::CMONTH( char * Date8 )<TD>
Returns name of the month of Date8.
<TR><TH ALIGN="LEFT">DATE()<TD>char * EXPN::DATE()<TD>
Returns system date.
<TR><TH ALIGN="LEFT">DAY()<TD>xbLong EXPN::DAY( char * Date8 )<TD>
Returns numeric value of the day of the month for Date8.
<TR><TH ALIGN="LEFT">DESCEND()<TD>EXPN::DESCEND()<TD>
Descend - used to create descending indices
<TR><TH ALIGN="LEFT">DTOC()<TD>char * EXPN::DTOC( char * Date8 )<TD>
Returns a date converted to format MM/DD/YY.
<TR><TH ALIGN="LEFT">EXP()<TD>xbDouble EXPN::EXP( xbDouble d )<TD>
Returns exponential for supplied value.
<TR><TH ALIGN="LEFT">IIF()<TD>
char * EXPN::IIF( xbShort, const char *,const char *)<TD>If statement
<TR><TH ALIGN="LEFT">INT()<TD>xbLong EXPN::INT( xbDouble d )<TD>
Converts any numeric value to an integer.
<TR><TH ALIGN="LEFT">ISALPHA()<TD>xbLong EXPN::ISALPHA( char * String )<TD>
Returns TRUE if string is alpha.
<TR><TH ALIGN="LEFT">ISLOWER()<TD>xbLong EXPN::ISLOWER( char * String )<TD>
Returns TRUE if string is lower case.
<TR><TH ALIGN="LEFT">ISUPPER()<TD>xbLong EXPN::ISUPPER( char * String )<TD>
Returns TRUE if string is upper case.
<TR><TH ALIGN="LEFT">LEFT()<TD>char * EXPN::LEFT( char * String, xbShort Len )<TD>
Returns <em>Len</em> characters from the left side of <em>String</em>.
<TR><TH ALIGN="LEFT">LEN()<TD>xbLong EXPN::LEN( char * String )<TD>
eturns the number of characters in the String.
<TR><TH ALIGN="LEFT">LOG()<TD>xbDouble EXPN::LOG( xbDouble d )<TD>
Returns the natural log of d.
<TR><TH ALIGN="LEFT">LOWER()<TD>char * EXPN::LOWER( char * String )<TD>
Converts a string to lower case.
<TR><TH ALIGN="LEFT">LTRIM()<TD>char * EXPN::LTRIM( char * String )<TD>
Eliminates leading white space from String.
<TR><TH ALIGN="LEFT">MAX()<TD>xbDouble EXPN::MAX( xbDouble d1, xbDouble d2 )<TD>
Returns the larger of two numeric arguments.
<TR><TH ALIGN="LEFT">MIN()<TD>xbDouble EXPN::MIN(xbDouble d1, xbDouble d2 )<TD>
Returns the smaller of two numeric arguments.
<TR><TH ALIGN="LEFT">MONTH()<TD>xbLong EXPN::MONTH( char * Date8 )<TD>
Returns numeric month for Date8.
<TR><TH ALIGN="LEFT">RECNO()<TD>xbLong EXPN::RECNO()<TD>
Returns the current record number of the associated DBF file
<TR><TH ALIGN="LEFT">REPLICATE()<TD>char * EXPN::REPLICATE( char * String, xbShort Count )<TD>
Replicates String Conut times.
<TR><TH ALIGN="LEFT">RIGHT()<TD>char * EXPN::RIGHT( char * String, xbShort Count )<TD>
Returns Count characters from the right side of String.
<TR><TH ALIGN="LEFT">RTRIM()<TD>char * EXPN::RTRIM( char * String )<TD>
Removes trailing white space from String.
<TR><TH ALIGN="LEFT">SPACE()<TD>char * EXPN::SPACE( xbShort Count )<TD>
Returns a buffer filled with Count spaces.
<TR><TH ALIGN="LEFT">SQRT()<TD>xbDouble EXPN::SQRT( xbDouble d )<TD>
Returns square root of d.
<TR><TH ALIGN="LEFT">STR()<TD>
char * EXPN::STR( xbDouble d )<hr>
char * EXPN::STR( xbDouble, xbShort )<hr>
char * EXPN::STR( xbDouble, xbShort, xbShort )
<TD>
Converts a number to a string.
<TR><TH ALIGN="LEFT">SUBSTR()<TD>char * EXPN::SUBSTR( char * String, xbShort StartPos, xbShort Len )<TD>
Returns a string form String starting at position StartPos for a length of Len.
<TR><TH ALIGN="LEFT">TRIM()<TD>char * EXPN::TRIM( char * String )<TD>
Same as RTRIM.
<TR><TH ALIGN="LEFT">UPPER()<TD>char * EXPN::UPPER( char * String )<TD>
Converts a string to upper case.
<TR><TH ALIGN="LEFT">VAL()<TD>xbLong EXPN::VAL( char * String )<TD>
Converts a string to an integer.
<TR><TH ALIGN="LEFT">YEAR()<TD>xbLong EXPN::YEAR( char * Date8 )<TD>
Returns numeric year from Date8.
</TABLE>
<br><br><br>
<TABLE BORDER>
<CAPTION ALIGN="TOP"><h3>Expression Processing Method List</h3></CAPTION>
<TR VALIGN="BASELINE">
<TR><TH ALIGN="LEFT">Method<TD>Description
<TR><TH ALIGN="LEFT">GetDoubleResult()<TD>Get xbDouble result from processed expression
<TR><TH ALIGN="LEFT">GetIntResult()<TD>Get a xbLong result from processed expression
<TR><TH ALIGN="LEFT">GetExpressionHandle()<TD>Get an expression's handle
<TR><TH ALIGN="LEFT">GetExpressionResultType(xbExpression *)<TD>Get expression result type
<TR><TH ALIGN="LEFT">GetStringResult()<TD>Get xbString & result from processed expression
<TR><TH ALIGN="LEFT">ParseExpression(char *,xbDbf *)<TD>Parse an expression
<TR><TH ALIGN="LEFT">ProcessExpression(xbExpression *)<TD>Process a parsed expression
</TABLE>
<br><hr>
<h3>Method Definitions</h3>
<hr>
<h3>Method xbDouble xbXBase::GetDoubleResult()</h3><br>
This method returns a xbDouble result from a processed expression.
<br><br>
See the program listing in chapter 5 for an example of how to use this method.
<hr>
<h3>Method xbLong xbXBase::GetIntResult()</h3><br>
This method returns a xbLong result from a processed expression.
<br><br>
See the program listing in chapter 5 for an example of how to use this method.
<hr>
<h3>Method xbExpression * xbXBase::GetExpressionHandle()</h3><br>
This method returns a handle to a recently parsed expression.
<br><br>
See the program listing in chapter 5 for an example of how to use this method.
<hr>
<h3>Method char xbXBase::GetExpressionResultType( xbExpression * e )</h3><br>
This method returns the result type for a given expression <em>e</em>.
<br>
<br>
<TABLE BORDER>
<CAPTION ALIGN="TOP"><h3>Method Return Codes</h3></CAPTION>
<TR VALIGN="BASELINE">
<TR><TH ALIGN="LEFT">Return Code Value<TD>Description
<TR><TH ALIGN="LEFT">C<TD>char * result from processed expression
- use GetStringResult()
<TR><TH ALIGN="LEFT">N<TD>xbDouble result from processed expression
- use GetDoubleResult()
<TR><TH ALIGN="LEFT">L<TD>xbLong (also logical) result from processed expression
- use GetIntResult()
</TABLE><br><br>
See the program listing in chapter 5 for an example of how to use this method.
<hr>
<h3>Method char * xbXBase::GetStringResult()</h3><br>
This method returns a xbString & result from a processed expression.
<br><br>
See the program listing in chapter 5 for an example of how to use this method.
<hr
<hr>
<h3>Method xbShort ParseExpression( char * exp, DBF * d)</h3><br>
This method parses expression <em>exp</em>.<br><em>d</em> is a pointer to
a database used for resolving any fieldname which does not contain the
<en>-></em> operator.
<br><br>
See the program listing in chapter 5 for an example of how to use this method.
<hr>
<h3>Method xbShort ProcessExpression( xbExpression * e )</h3><br>
This method processes parsed expression <em>e</em>.
<br><br>
See the program listing in chapter 5 for an example of how to use this method.
<br><br>
<hr>
<p><img src="xbase.jpg"><br><hr>
</BODY>
</HTML>
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