int_type.cpp

// long and long int are identical
// int is optional
// long is a signed type size of long in c++: at least 32 bits
long x;
long int x;

// long long is a signed type of at least 64 bits
long long int x;
long long;

// problem with following code when c is really large 
int i = 0;
int j = sqrt(c);
// runtime error
long res = i*i + j*j; // signed integer overflow because i*i + j*j is still treated as int type
// no runtime error by performing type cast
long res = (long) i*i + j*j;