Compilare: user.cpp: In function ‘int main()’: user.cpp:123:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<strlen(calc); ++i) ^ user.cpp:144:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=2; j<=strlen(sir)-1; ++j) ^ user.cpp:163:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(k=j+2; k<strlen(sir); ++k) ^ user.cpp: In function ‘int calcul(int, int, int, int)’: user.cpp:58:5: warning: control reaches end of non-void function [-Wreturn-type] } ^