第1題
關於下列C 程式碼，請說明程式執行後，程式碼編號27~33 的輸出，以
及其運算邏輯。（25 分）
#include <stdio.h>
#define SIZE 30
typedef enum direction {North, South, East=3, West} dir_t;
int f1(int a, int b) {
int x = 3.0/a;
double y = (a/2)*(b%3) + x;
return y;
}
int f2(dir_t d) {
d= (North+East)/2 > d? East: West;
return d;
}
int f3(int a, int b) {
if (b==a || b<=1) return a+b;
else if (a<=1) return b-a;
else return f3(a-b, a-1)+b+a;
}
int f4(int a, int b) {
int data[SIZE];
for (int i=1, k=0; i<a; i++) {
if (i%2==0) data[k++]=i;
}
return data[b];
}
unsigned int f5(unsigned int a, unsigned int b) { return (~a&b);
}
int main() {
printf("%d\n", f1(10, 4));
printf("%d\n", f2(South));
printf("%d\n", f3(6, 4));
printf("%u\n", f3(7, 4));
printf("%d\n", f4(20, 5));
printf("%d\n", f4(10, 4));
printf("%u\n", f5(4, 7));
return 0;
}
第2題
針對下列C++程式，請標示出Except 類別的f1, …, f6 函式中有問題的
函式，與說明其問題之原因；並請說明若將有問題的函式和程式碼刪除，
其程式執行後之輸出。（25 分）
#include <stdexcept>
#include <iostream>
#include <string>
using namespace std;
class Except{
public:
void f1(int c);
void f2();
void f3();
void f4();
void f5();
void f6();
};
int main() {
Except e;
e.f1(1);
e.f2();
e.f3();
e.f4();
e.f5();
e.f6();
return 0;
}
void Except::f1(int c) {
if (c<0)
throw out_of_range("large");
cout<<"exc1"<<endl;
}
void Except::f2() {
f1(-1);
}
void Except::f3() {
try {
f1(-1);
cout<<"ok"<<endl;
}catch(exception &e) {
cout<<"exc2"<<endl;
}
}
void Except::f4() {
try {
throw out_of_range("no");
}catch(out_of_range &e) {
cout<<e.what()<<endl;
cout<<"exc3"<<endl;
}
}
void Except::f5() {
try {
throw out_of_range("yes");
}catch(exception &e) {
cout<<"exc41"<<endl;
}catch(out_of_range &e) {
cout<<e.what()<<endl;
cout<<"exc42"<<endl;
}
}
void Except::f6() {
try {
throw out_of_range("ok");
}finally {
cout<<"exc6"<<endl;;
}
}
第3題
針對下列Java 程式碼，請完成統一塑模語言（UML）類別圖(a)~(e)；另
外請標示出錯誤程式碼行數並說明錯誤原因；以及說明若將錯誤行數程
式碼予以註解後，執行其程式的輸出。（25 分）
import java.io.*;
interface Pet {
public abstract int eat(int f);
};
class Dog implements Pet {
public Dog(int f) {food = f; }
public int eat(int f) {
food += f;
return food;
}
private int food;
};
public class Main{
public static void main(String[] args) {
Pet d1 = new Pet();
Pet d2 = new Dog();
Pet d3 = new Dog(5);
d1.eat(5);
d2.eat(5);
System.out.println("dog: "+d3.eat(5));
}
}
第4題
針對下列Python 程式碼，依序在兩個Terminal 執行server.py 和client.py
後，在client.py 輸入Tom 和quit；請說明client.py 的Terminal 之輸出內
容，並說明Line 03, 04, 05 程式碼的運作邏輯。（25 分）
# server.py
import socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.bind(('127.0.0.1', 7000))
s.listen(5)
print('wait for connection...')
while True:
conn, addr = s.accept()
print('connected by ' + str(addr))
indata = conn.recv(1024)
print('recv: ' + indata.decode())
if 'quit' in indata.decode():
outdata = 'bye '
else:
outdata = 'hi ' + indata.decode()
conn.send(outdata.encode())
conn.close()
if 'quit' in indata.decode():
break
print('listen...')
s.close()
#client.py
import socket
while True:
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(('127.0.0.1', 7000))
name = input('>name:')
print('send: ' + name)
s.send(name.encode())
indata = s.recv(1024)
s.close()
print('>' + indata.decode())
if 'quit' in name:
break