#include <iostream>
#include <cassert>

using namespace std;

int main()
{
    int i = 1;
    assert(i == 65);
    cout << "Hello world" << endl;
    return 0;
}
1 调试
2 我们可以利用它在某个程序里的关键假设不成立时，立刻停止该程序的执行并报错，从而避免更严重的错误

#include <iostream>
#include<climits>
using namespace std;

unsigned long getFact(unsigned short num) throw (const char*);

unsigned long getFact(unsigned short num) throw (const char*)
{
    unsigned long sum = 1;
    unsigned long max = ULONG_MAX;
    for ( int i=1; i<=num; i++)
    {
        sum *= i;
        max /= i;
    }
    if ( max < 1)
    {
        throw "too big data!!! ";
    }
    else
    {
        return sum;
    }
}

int main()
{
    try
    {
        unsigned short num = 13;
        unsigned long fac = getFact(num);
        cout << num << "!=" << fac << endl;
    }
    catch(const char *e)
    {
        cout << e << endl;
    }
    return 0;
}