The For Repetition Structure

Syntaxfor (initial-expression1, conditional-expression2, loop-expression3)

{ statement(s); }

Example:

for (int counter=1; counter <= 10; counter++;)

cout << counter << endl;

What the for Loop Looks Like:

The C++ for loop contains four major parts:

1. The value at which the loop starts.

2. The condition under which the loop is to continue.

3. The changes that are to take place for each loop.

4. The loop instructions.

Components of a typical for loop.

For Control Final value

Keyword Variable of control variable

Name

for (int counter = 1; counter <= 10; counter++)

initial value Loop increment

of control continuation of control

variable condition variable

Flowchart

Counter = 1

Counter <= 10 cout << counter <<endl;

counter++;

False

True

Body of loop Increment the counter variable

Example Program#include <iostream.h>

main(){

int time; // Counter variable.

// The loop starts here.

for(time = 1; time <= 5; time = time + 1)cout << "Value of time = " << time << "\n";

// The loop stops here.

cout << "This is the end of the loop.\n";}

More Than One Statement

You can have more than one statement in a C++ for loop.

By using

• the open braces { to indicate the beginning of the loop

• the close braces } to indicate the end of the loop.

Example Program: This program computes the distance a

body falls in feet per second, for the first 5 seconds of free fall as given by the equation: s = ½ at2

Wheres = the distance in feet.a = acceleration due to gravity t = time in seconds

#include <iostream.h>#define a 32.0

main(){

int time; // Counter variable.int distance; // Distance covered by the falling

// body.

// The loop starts here.

for(time = 1; time <= 5; time = time + 1)

{

distance = 0.5 * a * time * time;

cout << "Distance at the end of "

<< time << " seconds is ";

cout << distance << " feet.\n";

}

// The loop stops here.

cout << "This is the end of the loop.\n";

}

Your output should look like:

The Increment and Decrement Operators

Operator MeaningX++ Increment X after any operation with it.

(called post-incrementing).

++X Increment X before any operation with it.(called pre-incrementing).

X-- Decrement X after any operation with it. (called post-decrementing).

++X decrement X before any operation with it.(called pre-decrementing).

#include <iostream.h>

main(){

int count; // Program counter.int number1 = 0; // Number to post-increment.int number2 = 0; // Number to pre-increment.

for(count = 1; count <= 5; count++){

cout << "Post-incrementing number = " << number1++ << ", ";

cout << "Pre-incrementing number = "<< ++number2 << "\n";}

}

Your program should look like:

For Today:

For Loop Worksheet

Homework:

Read pages 87 to 95.

Quiz on Friday regarding For Loops!