| //Paul A. Gagniuc. An Introduction to Programming Languages: Simultaneous Learning in Multiple Coding Environments. Synthesis Lectures on Computer Science. Springer International Publishing, 2023, pp. 1-280. | |
| //Additional algorithm 27. It demonstrates the use of a single for-loop for two-dimensional arrays. It shows the traversal of a two-dimensional array by one for-loop structure. A 2D-array variable (A) is declared with mixed datatypes as before, namely with string literals and number literals. A string variable t is initially set to empty. A variable v is set to zero and it represents the main counter of the for-loop. Another two variables (ie. i and j) are initialized with value zero and are the main coordinates for element identification. Each dimension of array A is stored in variables n and m, namely the number of rows in n and the number of columns in m. The upper limit of the for-loop is calculated based on the two known dimensions n and m. Thus, m times n establishes the upper limit of the for-loop. Here, the value of the counter v from the for-loop is used to calculate the i and j values that are used as an index to traverse the array variable A. The value of variable j is computed as the v % m and the result of this expression indicates the reminder (ex. 5 mod 3 is 2). The secret to this implementation is a condition that increments a variable i (rows) each time j (columns) equals zero. Thus, in this manner this approach provides the i and j values that a nested for-loop provides. At each iteration, the value from an element is added to the content of variable t. Once the end of the for-loop is reached, the value collected in variable t is printed in the output for inspection. The end result is the enumeration of each value in the output, in a linear manner. Note that the source code is in context and works with copy/paste. | |
| using namespace std; | |
| int main() | |
| { | |
| string A[][2] = { | |
| {"a","b"}, | |
| {"c","d"}, | |
| {"e","f"}, | |
| {"g","h"}, | |
| }; | |
| string t = ""; | |
| int n = sizeof(A) / sizeof A[0]; | |
| int m = sizeof A[0] / sizeof(string); | |
| int i = 0; | |
| int j = 0; | |
| for (int v = 0; v < n*m; v++) { | |
| j = v % m; | |
| if(v!=0 && j == 0){i++;} | |
| t += to_string(v); | |
| t += " A["+to_string(i)+"]["; | |
| t += to_string(j)+"]="; | |
| t += A[i][j] + "\n"; | |
| } | |
| cout<<t; | |
| return 0; | |
| } | |