1. In linux+gcc, which of the following statements about the code is incorrect?____.
std::string& test_str()
{
std::string str=”test”;
return str;
}
int main()
{
std::string& str_ref=test_str();
std::cout<<str_ref<<std::endl;< p=”” style=”margin-right: auto; margin-left: auto;”></str_ref<<std::endl;<>
return 0;
}
A Compilation warning
B Returns a reference to a local variable, runtime unknown error
C Compiles and runs normally
D After removing all & from the code, the program can run normally
2. Assuming the definition of a two-dimensional array is “int a[3][4]={{3,4},{2,8,6}};”, what is the value of element a[2][1]?____.
A 0
B 4
C 8
D 6
3. Which of the following is the correct syntax for the template of sort?
A void sort(class A first, class A last, class B pred)
B void template(class A, class B)sort(A first, A last, B pred)
C template
D template
4. Which of the following statements is correct?
A Any existing operator in C++ can be overloaded
B const objects can only call const member functions
C Both constructors and destructors can be virtual functions
D Function overloading must have the same return type
5. For the following function call:
? fun(a+b,?3,?max(n-1,?b));? The number of actual parameters is____.
A 3
B 4
C 5
D 6
6. When two equivalent threads concurrently execute the following program, where a is a global variable initialized to 0, assuming printf, ++, and — operations are atomic, which output is definitely not possible?
void foo() {
if(a <= 0) {
a++;
}
else {
a–;
}
printf(“%d”, a);
}
A 01
B 10
C 12
D 22
7. In a 32-bit operating system with gcc compiler environment, what is the output of the following program?____.
#include
using namespace std;
class A {
public:
int b;
char c;
virtual void print() {
cout << “this is father’s function! ” << endl;
}
};
class B: A {
public:
virtual void print() {
cout << “this is children’s function! ” << endl;
}
};
int main(int argc, char * argv[]) {
cout << sizeof(A) << “” << sizeof(B) << endl;
return 0;
}
A 8 8
B 9 9
C 12 12
D 12 16
8. What is the difference between overloading and overriding?
A Overloading: allows multiple functions with the same name but different parameter lists
B Overloading: refers to the subclass redefining the method of a virtual function
C Overriding: refers to the subclass redefining the method of a virtual function
D Overriding: allows multiple functions with the same name but different parameter lists
Reference answers: 1~8: C A D B A A C AC
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