Question

Using PHP:

1. Write a function that:

• Given a numerical parameter in input, computes and prints all the prime numbers up to that value.

Example:

If input parameter is 10, output is "2, 3, 5, 7"

If input parameter is 100, output is "2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97"

2. Write a "tester function" that:

• Given a specific subset of inputs, tests the function described above.

Example, in pseudo code:

tester_function:   
   is output from prime_function(10) equal to "2, 3, 5, 7"? If yes, test passed
   is output from prime_function(0) equal to ""? If yes, test passed
   ...

Answer 1

For inputs less than 2 it returns ? I guess. If no then comment I can edit the code.

function p($n){
if($n<2){
echo "?";
return;
}
else{
for($i=2;$i<=$n;$i++){
if($i==2){
print "$i ";
continue;
}
else{
$f = 0;
for($j=2;$j<$i;$j++){
if($i%$j==0){
$f=1;
break;
}   
}
if($f==0){
echo "$i ";}
}
}
}
}