{"id":1849,"date":"2023-11-30T17:26:55","date_gmt":"2023-11-30T16:26:55","guid":{"rendered":"http:\/\/oopm.org\/?page_id=1849"},"modified":"2024-12-20T14:27:14","modified_gmt":"2024-12-20T13:27:14","slug":"3-4-using-array-and-for-loop","status":"publish","type":"page","link":"https:\/\/oopm.org\/?page_id=1849","title":{"rendered":"4.2 Array and for-loop"},"content":{"rendered":"
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A customer may have more than one account. In this section, we extend class Customer<\/code> to keep track of the accounts of a given customer.<\/p>\n\n\n\n

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We may use class Set<\/code> for this purpose, but we use this example to introduce Array<\/code>, which is another common collection object. An Array<\/code>-object is an indexed sequence of references to objects where each reference in the sequence may be denoted by an integer index.<\/p>\n<\/div>\n\n\n\n

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Accounts Array<\/p>\n<\/div>\n<\/div>\n\n\n\n

Class Array<\/code> is defined as follows:<\/p>\n\n\n\n

class<\/strong> Array(range: var<\/strong> integer, class<\/strong> ElmType:< Object):\n   put(R: ref<\/strong> ElmType):at[index: var<\/strong> integer]:\n      ...\n   get(index: var<\/strong> integer) -> R: ref<\/strong> ElmType:\n      ...<\/code><\/pre>\n\n\n\n
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  • The first parameter, range<\/code> of Array<\/code> is the number of elements in the Array<\/code>.<\/li>\n\n\n\n
  • The second paremeter, ElmType<\/code>, is the type of the elements in the Array<\/code> – similar to ElmType<\/code> for class Set<\/code>.<\/li>\n\n\n\n
  • It has a method put:at<\/code> with two parameters R<\/code> and index<\/code>. This method stores the reference at the position given by the value of index<\/code>.<\/li>\n\n\n\n
  • It has a method get<\/code>, which returns the reference stored at the position given by the parameter index<\/code>.<\/li>\n\n\n\n
  • As can be seen, put:at<\/code> and get<\/code> use another syntax for defining parameters than the one we have seen in previous examples using standard brackets and comma to separate the parameters. This syntax is explained in section