Compilare: user.cpp: In function ‘int main()’: user.cpp:22:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0; i<strlen(s); i++){ ~^~~~~~~~~~ user.cpp:23:25: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] if (s[i] >= 'a' && s[i] <= 'z' || s[i] >= '0' && s[i] <= '9'){ ~~~~~~~~~~~~^~~~~~~~~~~~~~ user.cpp:42:58: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (s[i+1] >= '0' && s[i+1] <= '9' && i+1 <= strlen(s)){ ~~~~^~~~~~~~~~~~