《Cracking the Coding Interview》——第12章：测试——题目2

2014-04-24 23:15

题目：你有一段程序，运行了十次每次都在不同的地方崩掉了。已知这段程序只用了标准C或C++库函数，请问有什么思路来找出问题所在。

解法：1. 时间戳每次都不同。2. 随机变量每次都不同。3. 局部变量的初值，每次可能不同，不过就算没初始化，很多时候那个无效值其实也是固定的，和编译器操作系统之类的相关。4. 外部依赖引起的问题，这点不太容易说清楚，简而言之：那是隔壁组的问题。5. 内存泄露，读到了非法区域，数据的确是不确定的。

代码：

// 12.2 A program crashes when it is run. After running it on a same machine for 10 times, it crashes every time on a different spot.
// It is single-threaded, and uses only C-standard libraries.
// Answer:
//    One different thing when the program is run every time, is the timestamp.
//    So you might check the code where functions about time is called, or timestamp is used.
//    To debug a bugged system, use logging strategy to aid you.
//    Two tips for debugging:
//        1. start printing log at both ends, every time you crashes, shrink the range of debugging by half. Use the ideas of binary search for debug.
//        2. print every suspicious variable if necessary.
int main()
{
    return 0;
}