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also be used to remind the programmer about specific objectives to be
met at a particular point in the program or the reason for specific
entries. In this example, however, the primary purpose was to enlighten
the reader about the purpose of a particular entry or operation.
The #include tells the computer to include the file to follow in the
C�� program. The �iostream.h� is a header file that sets up the
input-output path between the program and the disk operating system.
The class format defines the data type (in this case all floating points,
which means that a decimal point is included), and the public within the
{ } reveals that the variables value, voltage, and power are accessible
for operations outside the data structure.
Note that the main ( ) part of the program extends all the way
down to the bottom, as identified by the braces { }. Within this region
all the parameters of the network will be given values, all the calculations
will be made, and finally all the results will be provided. Next,
three resistor objects are established. Rtotal is defined as a floating variable,
and a voltage source object is introduced. The values of the resistors
are then entered, and the total resistance is calculated. Next,
through cout, the total resistance is printed out using the Rtotal just calculated.
The \n” at the end of the cout line calls for a carriage return to
prepare for the next cout statement.
On the next line, the magnitude of the voltage source is introduced,
followed by the calculation of the source current, which is then printed
out on the next line. Next the voltage across each resistor is calculated
and printed out by the succeeding lines. Finally, the various powers are
calculated and printed out.
When run, the output will appear as shown in Fig. 5.70 with the
same results obtained using PSpice and EWB. As noted above, do not
be perplexed by all the details of why certain lines appear as they do.
Like everything, with proper instruction and experience, it will all
become fairly obvious. Do note, however, that the first few lines set up
the analysis to be performed by telling the computer the type of operations
that need to be handled and the format of the data to be entered
and expected. There is then a main part of the program where all the
entries, calculations, and outputs are performed. When this program is
run, its flow is top-down; that is, one step follows the other without
looping back to certain points (an option to be described in a later program).
There was no need to number the lines or to include detailed
instructions. If all the comments were removed, the actual program
would be quite compact and straightforward, with most of the body of
the program being cout statements.
FIG. 5.70
Output results for the C�� program of Fig. 5.69.
COMPUTER ANALYSIS ⏐⏐⏐ 159