View Compilation Error

0_0_28656069_19230.cpp: In function 'BigNum operator+(BigNum, BigNum)':
0_0_28656069_19230.cpp:9:20: error: 'struct BigNum' has no member named 'clear'
         BigNum c;c.clear();int L=max(a.L,b.L);
                    ^
0_0_28656069_19230.cpp: In function 'void Input(BigNum&)':
0_0_28656069_19230.cpp:17:11: error: 'struct BigNum' has no member named 'clear'
         a.clear();char s[1000];scanf("%s",s);a.L=strlen(s);
           ^