# Second PHP Challenge

As the challenge we’ve given you last week was a real hit, we want to provoke you again!

So… you are given 2 integral numbers: a and b.

Request: Write a code sequence that interchanges the values of  these 2, without using additional variables.

### 3 thoughts on “Second PHP Challenge”

1. \$a= \$b-\$a;
\$b=\$a-\$b;
\$a=\$a+\$b;

2. \$a ^= \$b ^= \$a ^= \$b;

3. andreea.paraschiv

Well done, guys!

Our solutions were:
1.
\$a = \$a + \$b
\$b = \$a – \$b
\$a = \$a – \$b

2.
\$a = \$a * \$b;
\$b = \$a / \$b;
\$a = \$a / \$b;

3.
\$a = \$a ^ \$b;
\$b = \$a ^ \$b;
\$a = \$a ^ \$b;

4.
list(\$a, \$b) = array(\$b, \$a);
OR
list(\$a,\$b) = array_reverse(array(\$a,\$b));

5.
extract(array(‘a’=>\$b, ‘b’=>\$a));

6.
file_put_contents(‘a.txt’,\$a);
file_put_contents(‘b.txt’,\$b);

\$a = file_get_contents(‘b.txt’);
\$b = file_get_contents(‘a.txt’);

7.
\$a = \$a <> strlen(decbin(\$b));
\$a = \$b << (strlen(decbin(\$a)) – strlen(decbin(\$b))) ^ \$a;

So.. when it comes to web development, we do get creative!

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