View Compilation Error

0_0_5083777_31585.cpp: In function `int main()':
0_0_5083777_31585.cpp:9: error: `sum' undeclared (first use this function)
0_0_5083777_31585.cpp:9: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_5083777_31585.cpp: At global scope:
0_0_5083777_31585.cpp:12: error: `double sum(int)' used prior to declaration
0_0_5083777_31585.cpp:13: error: expected unqualified-id before '{' token
0_0_5083777_31585.cpp:13: error: expected `,' or `;' before '{' token