View Compilation Error

0_0_4622321_26459.c: In function `max':
0_0_4622321_26459.c:13: error: `len' undeclared (first use in this function)
0_0_4622321_26459.c:13: error: (Each undeclared identifier is reported only once
0_0_4622321_26459.c:13: error: for each function it appears in.)
0_0_4622321_26459.c:15: error: syntax error before "m"