String Data Types

In the case of string data types suitability is simply ... 

All data will be transmitted in a character string data type... 

The string data type is used to represent a sequence of ASCII characters. The string data types are commonly used to send and receive text messages fixtm user or any other communications port such as COM ports, Ethernet ports, etc. Apart from string control and string indicator, various objects that support string data type such as table, hst box, etc. are available. 

There are a large number of format string data type specifiers available for use with the fprintf function. Some of these are enumerated in Table 10.2. 

The Variant data type is the default data type in VBA. Like Excel itself, the Variant data type handles and interconverts between many different kinds of data integer, floating point, string, etc. The Variant data type automatically chooses the most compact representation. But if your procedure deals with only one kind of data, it will be more efficient and usually faster to declare the variables as, for example. Integer. 

Strings can be stored either as variable-length strings (the default data type) or as fixed-length strings. To declare a string variable as fixed-length, use the statement in a Dim statement (more about the Dim statement in Chapter 15)... 

VBA uses the Variant data type as the default data type for variables and arguments. The Variant data type permits Excel to switch between floatingpoint, integer and string variables as required. 

You can specify the data type of an argument passed to a Function procedure by using the As keyword in the Function statement. For example, if the Function procedure MolWt has two arguments, formula (a string) and decimals (an integer), then the statement... 

The differences between the InputBox function and the InputBox method are the following (i) default can be any data type and (ii) the additional argument type num specifies the data type of the return value. The values of type num and the corresponding data types are listed in Table 14-7. Values of type num can be added together. For example, to specify an input dialog box that would accept number or string values as input, use tiie value 1 + 2 = 3 for type num. 

Schemas are a newer development on the XML landscape. Like a DTD, a schema supplies the rules for building a document and indicates what tags may be used, what their attributes are, and how they relate to one another. Unlike a DTD, however, a schema has an additional level of specificity in that it can define data types. For example, a DTD might have a tag designated as , the content of which might be either numerical or a character string. A schema, by contrast, could ensure that the value entered was a number. This is clearly an appealing feature for the pharmaceutical industry, especially in the case of information exchange between databases or other applications making use of rigidly defined data types.

A data type is necessary to allow the RDBMS to accurately convert the data from an external representation, most often text in a file, to an internal representation of the data. For example, the external representation of a numeric value is a text string containing at least one numeral, and possibly a plus or minus sign or a decimal point. A text value may contain any valid text character, usually only printable characters from the ASCII set. The internal representation of the data is dependent upon the particular RDBMS and hardware being used. It is not necessary to know the exact internal representation of the data. The important thing to consider is which data type accurately represents the data for your purposes. 

The standard SQL data type Text has been used to store SMILES. This is appropriate because every SMILES is a valid text string. But not every text string is a valid SMILES. Without additional information about SMILES, the RDBMS cannot enforce any rules about which text strings ought to be in a column intended to contain SMILES. 

The use of Simplified Molecular Input Line Entry System (SMILES) as a string representation of chemical structure makes possible much of what has been discussed in earlier chapters of this book. A chemical reaction could be represented as a collection of SMILES, some identified as reactants and some as products. It is possible to define a table to do this, or perhaps use some arrays of character data types, but a syntax extension of standard SMILES allows reaction to be expressed easily. SMIRKS is an extension of SMILES and SMiles ARbitrary Target Specification (SMARTS). It is used to represent chemical transformations. SMIRKS can also be used in a transformation function to combine SMILES reactants to produce SMILES products. 

The last Perl data type that will be considered is the hash. Hashes are similar to arrays in many respects. They hold multiple values, they can be indexed, and they can be looped over, one element at a time. What distinguishes hashes from arrays is that the elements of a hash are unordered, and the indexes are not numbers but strings. A few examples will clarify this ... 

Data types treated by MADCAP include real numbers (no distinction is made between floating-point and integer), complex numbers, character strings, matrices with real elements, sets of natural numbers, and arrays of arbitrary elements (77). Notation and facilities exist for character-string manipulation matrix operations of addition, subtraction, multiplication, inversion, and transposition set-theoretic operations of complementation, union, intersection, subtraction, and symmetric subtraction (exclusive or). When the set-theoretic operations were added to the language, set-theoretic comparators for use in conditional expressions and other language extensions to facilitate the programming of combinatorial calculations were incorporated, as well (78). 

The dollar sign was chosen because, of all the characters available on the keyboard, it most suggested the letter s in the word string. (Note that strings were always a primitive data type and not an array of characters, as in the C programming language.)... 

Data type A set of instances of an application concept with an associated set of legal operations in which instances of the concept can participate. Some data types are primitive (e.g., integer, string) insofar as they are supported by the DBMS directly (and, hence, are not application specific). Some are application specific (e.g., gene). Some data types are atomic (e.g., integer) and some are complex (e.g., address, comprising street name, state, etc.). Some data types are scalar (e.g., integer) and some are bulk, or collection (e.g., sets, lists). 

For exampie, a singie document may use namespaces to take eiement definitions from more than one schema, with each eiement being vaiidated against the appropriate schema. Schemas aiso ailow eiement content to be restricted to specified data types (string, booiean, decim number, etc.). Ai-though the Worid Wide Web Consortium has issued a specification for XML schemas, other schema ianguages are aiso used. 

Behavioral descriptions for these applications usually contain various control structures such as conditional branches, loops and conditional jumps. In addition, they contain various data types such as bit strings, integer, boolean, arrays and records. In order to synthesize efficient circuits from such a behavioral description, it is important to deal with such structures cleverly, especially in scheduling and datapath allocation. However, most of conventional scheduling and allocation algorithms do not deal with such structures explicitly. 

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