Compilare: user.cpp: In function ‘void calc(char*, int&, int&)’: user.cpp:16:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=J;j<strlen(x);j++) ^ user.cpp:35:75: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if ((strchr(semn,x[j])!=0&&x[j-1]>='0'&&x[j-1]<='9')||j==strlen(x)) ^ user.cpp: In function ‘int main()’: user.cpp:56:15: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] t[p-S]=NULL; ^