fzuoop期中练习

5-1 科学计数法的值

#include<iostream>
#include<sstream>
#include<string>
#include<cstdio>
using namespace std;

int main()
{
    string str;
    while(cin >> str)
    {
        string ans;
        bool flag,IsSign,IsMinus;
        int i;
        int len = str.size();

        string::size_type loc = str.find("^");
        if (str[loc + 1] != '-')
        {
            IsSign = false;
        }
        else
        {
            IsSign = true;
        }

        if (!IsSign)
        {
            int intcnt = 0;
            for (i = 0; str[i] != '*' && str[i] != '.'; i++)
            {
                ans += str[i];
                intcnt++;
            }
            if (str[i] == '.')
            {
                i++;
            }
            int cnt = 0;
            for (; str[i] != '*'; i++)
            {
                ans += str[i];
                cnt++;
            }

            int record;
            string tmp;
            stringstream ss;
            if (loc == string::npos)
            {
                record = 1;
            }
            else
            {
                for (i = loc+1; i < len; i++)
                {
                    tmp += str[i];
                }
                ss << tmp;
                ss >> record;
            }

            if (record < cnt)
            {
                flag = false;
            }
            else
            {
                flag = true;
            }

            int len1 = ans.size();
            if (flag)
            {
                cout << "The actual value for " << str << " is " << ans;
                for (i = record - cnt; i > 0; i--)
                {
                    cout << "0";
                }
                cout << endl;
            }
            else
            {
                cout << "The actual value for " << str << " is ";
                for (i = 0; i < intcnt + record; i++)
                {
                    cout << ans[i];
                }
                cout << ".";
                for (i = intcnt + record; i < len1; i++)
                {
                    cout << ans[i];
                }
                cout << endl;
            }
        }
        else
        {
            if (str[0] == '-')
            {
                str.erase(0,1);
                IsMinus = true;
            }
            else
            {
                IsMinus = false;
            }
            len = str.size();
            int intcnt = 0;
            for (i = 0; str[i] != '*' && str[i] != '.'; i++)
            {
                ans += str[i];
                intcnt++;
            }
            if (str[i] == '.')
            {
                i++;
            }
            for (; str[i] != '*'; i++)
            {
                ans += str[i];
            }

            int record;
            string tmp;
            stringstream ss;
            if (loc == string::npos)
            {
                record = 1;
            }
            else
            {
                if (IsMinus)
                {
                    for (i = loc + 1; i < len; i++)
                    {
                        tmp += str[i];
                    }
                }
                else
                {
                    for (i = loc + 2;i < len;i++)
                    {
                        tmp += str[i];
                    }
                }
                ss << tmp;
                ss >> record;
            }
            cout << "The actual value for " << str << " is ";
            if (IsMinus)
            {
                cout << "-";
            }
            cout  << "0.";
            for (i = 0; i < record - intcnt; i++)
            {
                cout << "0";
            }
            cout << ans << endl;
        }
    }
    return 0;
}

5-3 不能用循环是一件多么悲伤的事

这道题虽然AC了，总感觉递归的姿势不正确= =

#include<iostream>
#include<iomanip>
#include<cstdio>
#include<cstdlib>
using namespace std;

int N;

void func(int num,int cnt)
{
    if (num <= N)
    {
        if (num + cnt <= N)
        {
            printf("%-2d+%2d = %-2d ",num,cnt,num+cnt);
            //cout << setiosflags(ios::left) << setw(2) << num << " + " << setiosflags(ios::right) << setw(2) << cnt << " = " << setiosflags(ios::left) << setw(2) << num+cnt << " ";
            func(num,cnt+1);
        }
        cout << endl;
    }
    if (num > N)
    exit(0);
    func(num+1,0);
}

int main()
{
    scanf("%d",&N);
    func(0,0);
    return 0;
}