5.1 Arrays

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So far in constructing our building we have named each brick (variable). That is fine for a small number of bricks, but what happens when we want to construct something larger? We would like to point to a stack of bricks and say, "That's for the left wall. That's brick 1, brick 2, brick 3. . . ."

Arrays allow us to do something similar with variables . An array is a set of consecutive memory locations used to store data. Each item in the array is called an element . The number of elements in an array is called the dimension of the array. A typical array declaration is:

 // List of data to be sorted and averaged int    data_list[3]; 

This declares data_list to be an array of the three elements data_list[0] , data_list[1], and data_list[2] , which are separate variables. To reference an element of an array, you use a number called the subscript (the number inside the square brackets [ ]). C++ is a funny language and likes to start counting at 0, so these three elements are numbered 0-2.

Common sense tells you that when you declare data_list to be three elements long, data_list[3] would be valid. Common sense is wrong: data_list[3] is illegal.

Example 5-1 computes the total and average of five numbers .

Example 5-1. five/five.cpp
 #include <iostream> float data[5];  // data to average and total  float total;    // the total of the data items  float average;  // average of the items int main(  ) {     data[0] = 34.0;     data[1] = 27.0;     data[2] = 46.5;     data[3] = 82.0;     data[4] = 22.0;     total = data[0] + data[1] + data[2] + data[3] + data[4];     average =  total / 5.0;     std::cout << "Total " << total << " Average " << average << '\n';     return (0); } 

Example 5-1 outputs:

 Total 211.5 Average 42.3 
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Practical C++ Programming
Practical C Programming, 3rd Edition
ISBN: 1565923065
EAN: 2147483647
Year: 2003
Pages: 364

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