|getline(cin,str)之前要getchar()|7-8 Left-pad (20分)

#include <iostream>
#include <cstdio>
#include <vector>
using namespace std;
vector<char> v;
int main()
{
    
    
    int n;
    char c;
    scanf("%d %c",&n,&c);//15 _
    string before;
    getchar();
    getline(cin,before);
    int len=before.length();
    if(n>len){
    
    
        int diff=n-len;//15-11=4
        for(int i=0;i<diff;i++){
    
    
            v.push_back(c);
        }
        for(int j=0;j<len;j++){
    
    
            v.push_back(before[j]);
        }
        for(int i=0;i<v.size();i++){
    
    
            cout<<v[i];   
        }
    }else if(n<len){
    
    
        for(int i=len-n;i<=len-1;i++){
    
    
            cout<<before[i];
        }
    }else{
    
    
        cout<<before;
    }
    
    return 0;
}