Pascal Programming Arrays and String Type

Pascal Programming The Array What if you had a list of 100 values you wanted to store. That would require 100 variables—an unwieldy solution. Instead, Pascal provides an array. The array consists of a two-part name. Part 1 stays constant and part 2 changes. continue . . .

Pascal programming Array declaration and syntax . . . type var SmallArray = array[1 .. 5] of integer; var Score: SmallArray The type after the of is the component type All five variables have this type. The variables are called indexed variables. continue . . .

Pascal Programming Inside the square brackets –array [ 1 .. 5]– is the index or index expression or subscript. The value of an indexed variable becomes an element or value of the array. Score := 1 The array is declared just like other types. type array [index_type] of component type The index_type can be an ordinal or subrange. Component_type may be any Pascal type.

Pascal Programming Once an array type has been declared . . . a particular array is declared just like other variables. In summary . . . An array variable creates the locations An array value occurs in each used location. An element of the array will be any value in it. The array index identifies locations and values in an array. An indexed variable identifies names the location.

Pascal Programming An array illustrates the structured type. Up to now, we have used simple types except string. Pascal programmers may created compound types called structured type. In Turbo Pascal, the size of the array must be declared. Thus, we must declare the largest anticipated size for the array. Partially filled arrays present problems. We solve the problem with a variable Last that marks the last location filled with a value.

Pascal Programming A move through the array can be accomplished with a for loop. This is called sequential access. The alternative is random access. When data is read in in sequence the array fills from beginning to end. Random access allows data to be placed at an indexed location.

Pascal Programming Turbo Strings A string may be thought of as an array of char. Var Caption : string [20]; Caption := ‘Seize the day’ We read into array[11] p . . . The meaning changes. continue . . .

Pascal Programming Procedures and functions can use type string. . . But the string needs to be declared as a type. Then, the string type performs like an array. String[20] is a definition but . . . String20 =string [20] is a declaration of type. Functions, delivering a value, cannot return to an array be it can to a string type.

Pascal Programming Turbo Pascal provides a variety of predefined functions and procedures to manipulate string type. Included are . . . Length returns the length of a subset of string. Pos identifies the position of a value. Upcase returns an upper case char. Delete eliminates defined values. Copy copies a subset of string.