Programming in C

Functions and Arrays
149
Program 8.13 Continued
printf ("\n");
}
}
Program 8.13
Output
Original matrix:
7 16 55 13 12
12 10 52 0 7
-2 1 2 4 9
Multiplied by 2:
14 32 110 26 24
24 20 104 0 14
-4 2 4 8 18
Then multiplied by -1:
-14 -32 -110 -26 -24
-24 -20 -104 0 -14
4 -2 -4 -8 -18
The main routine defines the matrix sampleValues and then calls the displayMatrix
function to display its initial values at the terminal. Inside the displayMatrix routine,
notice the nested for statements.The first or outermost for statement sequences
through each row in the matrix, so the value of the variable row varies from 0 through
2.For each value of row, the innermost for statement is executed.This for statement
sequences through each column of the particular row, so the value of the variable
column ranges from 0 through 4.
The printf statement displays the value contained in the specified row and column
using the format characters %5i to ensure that the elements line up in the display. After
the innermost for loop has finished execution—meaning that an entire row of the
matrix has been displayed—a newline character is displayed so that the next row of the
matrix is displayed on the next line of the terminal.
The first call to the scalarMultiply function specifies that the sampleMatrix array
is to be multiplied by 2. Inside the function, a simple set of nested for loops is set up to
sequence through each element in the array.The element contained in
matrix[row][column] is multiplied by the value of scalar in accordance with the use
of the assignment operator *=. After the function returns to the main routine, the
displayMatrix function is once again called to display the contents of the
sampleMatrix array.The program’s output verifies that each element in the array has, in
fact, been multiplied by 2.