Download Decision Structures

C#
and the .NET Framework
Control Structures
Operator
Symbol
Meaning
Example
<
less than
31 < 25
is false
<=
less than or equal to
464 <= 7213
is true
>
greater than
-98 > -12
is false
>=
greater than or equal to
9 >= 99
is false
==
equal to
9 == 12 + 12
is false
!=
not equal to
292 != 377
is true
Java relational and equality operators
The if Statement
Type bool Two values, true and false
if (condition)
if_true_statement
The condition is a bool expression. If it is
true then the if_true_statement will be
executed
if (x >2)
y = x + 17;
Entry
int item1 = 25;
int item2 = 12;
Item2 = item1+15;
Exit
The sequence control flow
condition
true
if_true_statement
false
Control flow for the if statement
The if-else statement
Choose between two alternatives
if (condition)
if ( x <= 20)
if_true_statement
x += 5;
else
else
if_false_statement
x+=2;
True
if_true_statement
Condition
False
if_false_statement
Flow chart for the if-else statement
Blocks
Group a sequence of statements inside braces
{
x = 5;
y = -8;
z = x*y;
}
May use a block in an if or if-else statement
Scientific Notation
Small or large numbers are hard to read
Use exponents instead
3.937E-8 instead of .00000003937
5.88E12 instead of 5,880,000,000,000
E or e
E12 or E+12
Type double
Provides about 16 decimal places
double length = 173.24E5; // exponent
double height 1.83;
// fixed
+,-,*,/ operators
Formatted Output
{0:E}
Scientific default (three decimal
places)
{0:F2} Fixed-point, two decimal places
{O:G} General, default (same as {0})
while statement
Provides repetition
while (condition)
while_true_statement
while (x < 10)
x += 2;
If x = 5, then x becomes 7, 9 before loop stops
while (x < 10)
x -= 4;
//does not terminate if x starts at 5
False
Condition
True
while_true_statement
Flow chart for the while loop
Read the quantity of scores;
while(count < quantity) {
Read the next score;
Add the score to the total so far;
Increment the count of scores;
}
Display the quantity and the total;
Pseudocode for the sum of test scores problem