Compilare: user.cpp: In function ‘int main()’: user.cpp:16:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(strchr(r+j,')')!=NULL && j<strlen(r)) ^ user.cpp:19:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(r[j]==' ' && j<strlen(r)) ^ user.cpp:22:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(j<strlen(r) && r[j]>='0' && r[j]<='9') ^ user.cpp:26:14: warning: statement has no effect [-Wunused-value] k*10; ^