View Compilation Error

0_0_17118914_13000.cpp: In function 'int LCS(const char*, const char*)':
0_0_17118914_13000.cpp:24:25: error: 'strlen' was not declared in this scope
     int xlen=strlen(str1);       
                         ^
0_0_17118914_13000.cpp: In function 'int main()':
0_0_17118914_13000.cpp:64:35: error: 'strlen' was not declared in this scope
             int len1=strlen(str[i]);
                                   ^