Computer Programming Concepts and Visual Basic David I. Schneider

The body of a For...Next loop can contain any sequence of Visual Basic statements. In particular,
it can contain another For...Next loop. However, the second loop must be completely
contained inside the first loop and must have a different control variable. Such a configuration
is called nested loops. Figure 5-5 shows several examples of valid nested loops.
FIGURE 5-5 Nested Loops
EXAMPLE 4
Write a program to display a multiplication table for the integers from 1 to 4.
SOLUTION:
In the following program, j denotes the left factors of the products, and k denotes the right factors. Each
factor takes on a value from 1 to 4. The values are assigned to j in the outer loop and to k in the inner loop.
Initially, j is assigned the value 1, and then the inner loop is traversed four times to produce the first row
of products. At the end of these four passes, the value of j will still be 1, and the value of k will have been
incremented to 5. The picTable.Print statement just before Next j guarantees that no more products will
be displayed in that row. The first execution of the outer loop is then complete. Following this, the statement
Next j increments the value of j to 2. The statement beginning For k is then executed. It resets the
value of k to 1. The second row of products is displayed during the next four executions of the inner loop
and so on.
Private Sub cmdDisplay_Click()
Dim j As Integer, k As Integer
picTable.Cls
For j = 1 To 4
For k = 1 To 4
picTable.Print j; “x”; k; “=”; j * k,
Next k
picTable.Print
Next j
End Sub
Object Property Setting
frmMultiply Caption Multiplication Table
cmdDisplay Caption Display Table
picTable
For...Next Loops 145