View Compilation Error

0_0_16447046_12003.cpp: In function 'int main()':
0_0_16447046_12003.cpp:21:15: error: 'strlen' was not declared in this scope
    if(strlen(s)==1&&s[0]=='0') break;
               ^
0_0_16447046_12003.cpp:23:27: error: 'memset' was not declared in this scope
    memset(c,'\0',sizeof(c));
                           ^
0_0_16447046_12003.cpp:24:26: error: 'strlen' was not declared in this scope
    for(i=0,j=0,n=strlen(s);i<n;)  //将算数表达式，也就是中缀表达式变成后缀表达式，放到c中
                          ^
0_0_16447046_12003.cpp:89:22: error: 'strlen' was not declared in this scope
    for(i=0,n=strlen(c);i<n;i++)
                      ^