View Compilation Error

0_0_1529957_1595.cpp: In function `int main()':
0_0_1529957_1595.cpp:4: error: expected primary-expression before "register"
0_0_1529957_1595.cpp:4: error: expected `;' before "register"
0_0_1529957_1595.cpp:7: error: `sum' undeclared (first use this function)
0_0_1529957_1595.cpp:7: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_1529957_1595.cpp:8: error: `i' undeclared (first use this function)
0_0_1529957_1595.cpp:8: error: `n' undeclared (first use this function)