1. Design a program, when you enter an integer number that is greater than 100 and less than 1000, the output result is its inverse order. For example, when you input number 563, the output result is 365.

2. According to the following formula, please calculate the value of Pai.   

Pai/4=1-1/3+1/5-1/7+...

1.
#include<iostream.h>
int reverse(int n)
{
    int i=0;
    while(n!=0)
    {        
        i=i*10+n%10;
        n=n/10;
    }
return i;
}
void main()
{
    int n;
    cin>>n;
    if(n>100&&n<1000)
    cout<<reverse(n);
}

2.
#include<iostream.h>
void main()
{
    int i,s=0,flag=1;
    for(i=1;i<50;i=i+2)//50可换，来控制精度//
    {
        s+=flag/i;
        flag=-flag;
    }
    s*=4;
    cout<<"Pai="<<s;
}

收到的鲜花

• mxs810 于 2010-09-15 11:55 送鲜花  5朵  

第一题：#include <iostream>

using namespace std;

int main()
{
    int n;
    do
    {
        cout<<"please enter the intger range 100 form 1000:"<<endl;
        cin>>n;
        if(!cin)
            break;
        if(n>=1000||n<=100)
            cout<<"wrong data!"<<endl;
        else
        {
            int i,j,k;
            i=n%10;//个位
            j=n/10%10;//十位
            k=n/100;//百位
            cout<<"The number is:"<<i<<j<<k<<endl;
        }

        cin.clear();
    }while(cin);

    return 0;
}
第二题参照二楼吧，写得很简洁

关注中

顶一二楼的

问题应该解决了吧。
恭喜楼主。