Compilare: user.cpp: In function ‘int main()’: user.cpp:24:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0;j<strlen(s);j++) ^ user.cpp:45:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0;j<=(strlen(s)-1)/2;j++) ^ user.cpp:68:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (kk=0;kk<=strlen(s);kk++) ^ user.cpp:74:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (kk>strlen(s)/2) ^ user.cpp:69:20: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if (s[kk]==car) ^