View Compilation Error

0_0_13810725_15416.cpp: In function 'int main()':
0_0_13810725_15416.cpp:13:55: error: 'memset' was not declared in this scope
 #define CLR(NAME,VALUE) memset(NAME,VALUE,sizeof(NAME))
                                                       ^
0_0_13810725_15416.cpp:147:4: note: in expansion of macro 'CLR'
    CLR(walk,0);
    ^