View Compilation Error

0_0_10415626_11462.c: In function `main':
0_0_10415626_11462.c:14: error: `sum_days' undeclared (first use in this function)
0_0_10415626_11462.c:14: error: (Each undeclared identifier is reported only once
0_0_10415626_11462.c:14: error: for each function it appears in.)
0_0_10415626_11462.c:15: error: 'for' loop initial declaration used outside C99 mode
0_0_10415626_11462.c:24: error: syntax error at end of input