Compilare: main.cpp: In function 'int main()': main.cpp:21:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<strlen(mes);i++) ~^~~~~~~~~~~~ main.cpp:25:24: warning: suggest parentheses around '&&' within '||' [-Wparentheses] if(mes[i]>='a' && mes[i]<='z' || mes[i]>='A' && mes[i]<='Z') { ~~~~~~~~~~~~^~~~~~~~~~~~~~