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Pascal Programming

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.

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Pascal Programming

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  1. Pascal Programming Arrays and String Type

  2. 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 . . .

  3. Pascal programming • Array declaration and syntax . . . • type • 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 . . .

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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 . . .

  9. 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.

  10. 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.

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