View Compilation Error

0_0_4803370_1031.cpp: In function `void merge(int*, int, int, int)':
0_0_4803370_1031.cpp:14: error: `b' undeclared (first use this function)
0_0_4803370_1031.cpp:14: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_4803370_1031.cpp: At global scope:
0_0_4803370_1031.cpp:49: error: `int b[1000000]' used prior to declaration