C++ How to Program, Ninth Edition

Nested Range-Based for Statements

To process the elements of a two-dimensional array, we use a nested loop in which the outer loop iterates through the rows and the inner loop iterates through the columns of a given row. Function printArray’s nested loop is implemented with range-based for statements. Lines 27 and 30 introduce the C++11 auto keyword, which tells the compiler to infer (determine) a variable’s data type based on the variable’s initializer value. The outer loop’s range variable row is initialized with an element from the parameter a. Looking at the array’s declaration, you can see that the array contains elements of type

array< int, columns >

so the compiler infers that row refers to a three-element array of int values (again, ...