Difference between revisions of "Loops"

Revision as of 16:13, 6 March 2007

An Introduction

A loop is a control structure that repeatedly executes a sequence of steps for as long as a test condition evaluates to true. What does iterate mean?

Types of Loops

• while
• for -Roger
• nested loops -Roger

Test Condition

Loops use the test condition to decide whether or not to enter the body of the loop.

Scope

A loop will enter the body if and only if the test condition evaluates to true.

Infinite Loops

An infinite loop is any loop that continues to repeat forever. There are situations where this is useful, but if you didn't intentionally program it in, then it causes a fatal error for your program. These occur if the test condition in your loop will never be false. Here are a few examples of infinite loops:

while(true) //always true
{
}
------------------------------------------------
for(int i = 0; i < 20; i++) //counter reset to 0 every time
{
    i = 0;
}
------------------------------------------------
for(int i = 0; i < 5e9; i++) //integers can't be as big as 5e9(5*10^9), so i will overflow to negative
{
}

Additional Information

• Multiple Control Statements
• brief explanation of do-while loops (and why bottom testing loops are not ideal)
• Running Totals and Sentinel Values
• Review Questions and Exercises