一、預處理指令

問題：輸入一些WORD,判斷有沒有首字母大寫的兩個相同的詞

 1 #include<iostream>
 2 #include<string>
 3 
 4 using namespace std;
 5 
 6 int main()
 7 {
 8     string currWord, preWord;
 9     cout << "Enter some words:(ctrl+z to end)" << endl;
10     while (cin >> currWord)
11     {
12 #ifndef NDEBUG
 
13         cout << endl << "調試：" << currWord << endl;  //這是調試用的
14 #endif
15         if (!isupper(currWord[0]))
16             continue;
17         if (currWord == preWord)
18             break;
19         else preWord = currWord;
20     }
21     if (currWord == preWord&&!currWord.empty())
 
22     {
23         cout << "The repeated word:" << currWord << endl;
24     }
25     else
26         cout << "沒有重復的！" << endl;
27     system("pause");
28 }

關閉預處理：

解決資源方案--demo--右鍵“屬性”--c++--命令行----附加選項：/DNDEBUG

結果：

二、預處理常量

 1 #include<iostream>
 2 #include<string
 
>
 3 
 4 using namespace std;
 5 
 6 int main()
 7 {
 8     cout << "文件：" << __FILE__ << endl<<"行：" << __LINE__ << endl<<"日期：" << __DATE__ << endl<<"時間：" << __TIME__ << endl;
 9     system("pause");
10 }

三、assert斷言

 1 #include<iostream>
 2 #include<assert.h>
 3 
 4 using namespace std;
 5 
 6 int add(int x, int y)
 7 {
 8     return x * y;
 9 }
10 int main()
11 {
12     int result;
13     result = add(1, 2);
14     assert(result == 3);
15     cout << result << endl;
16     system("pause");
17 }

斷言也用來調試，與預定義一樣，受附加選項/DNDEBUG控制

使用預處理器進行調試