Iteration

Example 1 - for

C

#include <stdio.h>
int main () {
    for(int x=1;x<10;x++){
        puts("hello");
    }
}

PHP

<?php
    for ($x=1; $x<10; $x++) {
        echo "hello";
     }
?>

Python

~~x = 1~~
~~while x < 10:~~
~~print("hello")~~
~~x += 1~~

for _ in range(1,10):
print("hello:",_)

Bash

#!/bin/bash
for (( x=1; x<=10; x++ ))
do
echo "Welcome $x times"
done

Example 2 - while

C

#include <stdio.h>
int main () {
    int x = 1;
    while (x++ < 10) {
        puts("hello");
    }
}

#include <stdio.h>
int main () {
    register int x = 1; // Look at the difference in the .asm code
                         // gcc -o while.asm -S while1.c
    while (x++ < 10) {
        puts("hello");
    }
}

PHP

<?php
    $x = 1;
    while ($x < 10){
        print("hello");
        $x += 1;
    }
?>

Python

x = 1
while x < 10:
print("hello")
x += 1

Bash

#!/bin/bash
x=0
while [ $x -lt 10 ]
do
echo hello
x=$[$x+1]
done

Note: I have not done any input in the above examples. Input of course can be done the same way as we did for Selection.

Hands on

The same as the previous hands on. Copy the 4 files into iteration1.c, etc. and run them.
ssThen do it again for the second set of examples using iteration2.c etc.

Then:

Modify the one of the programs to take an input of the number of times to loop.

Home Work

Modify (or create new) all 8 programs to take input

Choose one of the languages and write a program to display the first n fibonacci numbers. Where in is input.

A fibonacci number is the sum of the previous 2 numbers

The first number is 0
The second number is 1
The third number is 1
The forth number is 2
The fifth number is 3
etc...