View Compilation Error

0_0_6051742_21726.cpp: In function `int main()':
0_0_6051742_21726.cpp:4: error: `scanf' undeclared (first use this function)
0_0_6051742_21726.cpp:4: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_6051742_21726.cpp:9: error: `cal_pix_line' undeclared (first use this function)
0_0_6051742_21726.cpp:11: error: `printf' undeclared (first use this function)