echo vs echo intval PHP

Question

Please can some one explain the result differences below

echo intval(1e10); 

Output 1410065408

echo 1e10; 

Output 10000000000

Answer 1

A signed integer has a maximum value. On 32-bit systems, that's 2^16 or 2147483647. When intval-ing a number that's larger, it will overflow. The value you found can also calculated:

php > echo 1e10 % (2147483647);
1410065408