Today, we will look at some more C++ statements and the do/while loop.
"do/while" Repetition Structure
"break" and "continue" Statements
Logical Operators
Structured Programming Summary
"do/while" Repetition Structure
•Similar to while structure
–Makes loop
continuation test at end, not beginning
–Loop body
executes at least once
•Format
do {
statement
"break" and "continue" Statements
•
break statement
–
Immediate exit from while, for, do/while,
switch
–
Program continues with first statement after
structure
•
Common uses
–
Escape early from a loop
•
continue statement
–
Used in while, for, do/while
–
Skips remainder of loop body
Logical Operators
•
Used as conditions in loops, if statements
•
&& (logical AND)
–
true if both conditions are true
if ( gender == 1 && age
>= 65 )
++seniorFemales;
++seniorFemales;
•
|| (logical OR)
–
true if either of condition is true
if ( semesterAverage >= 90 ||
finalExam >= 90 )
cout << "Student grade is A" << endl;
cout << "Student grade is A" << endl;
•
! (logical NOT, logical negation)
–
Returns true when its condition is false,
& vice versa
if ( !( grade == sentinelValue ) )
cout << "The next grade is " << grade << endl;
cout << "The next grade is " << grade << endl;
Alternative:
if (
grade != sentinelValue )
cout << "The next grade is " << grade << endl;
cout << "The next grade is " << grade << endl;
Structured Programming Summary
•
Structured programming
–
Programs easier to understand, test, debug and
modify
•
Rules for structured programming
–
Only use single-entry/single-exit control
structures
–
Rules
1) Begin with the “simplest flowchart”
2) Any rectangle (action) can be replaced by two
rectangles (actions) in sequence
3) Any rectangle (action) can be replaced by any
control structure (sequence, if,if/else, switch,
do/while or for)
4) Rules 2 and 3 can be applied in any order and
multiple times
•
All programs broken down into
–
Sequence
–
Selection
•
if, if/else, or switch
•
Any selection can be rewritten as an if
statement
–
Repetition
•
while, do/while or for
•
Any repetition structure can be rewritten as a while
statement
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