《C++程序设计原理与实践》部分习题答案 4

来源：互联网发布：百知尚行是培训机构吗编辑：程序博客网时间：2024/05/22 11:39

10.1

#include<iostream>#include<fstream>#include<string>using namespace std;int main(){cout<<"Please enter input file name: ";string name;cin>>name;ifstream ist(name.c_str());if(!ist) perror("can't open input file");int temp,sum=0;while(ist>>temp){if(temp!=' ') sum=sum+temp;}cout<<"sum= "<<sum<<endl;system("pause");}

10.2

#include<iostream>#include<fstream>using namespace std;int main(){cout<<"创建文件raw_temps.txt ..."<<endl;ofstream ost("E:\\raw_temps.txt");if(!ost) cout<<"无法创建文件..."<<endl;int hour;double temperature;cout<<"输入时间 温度格式数据(输入0~24范围外的时间退出输入)"<<endl;while(1){cin>>hour;if(hour<0||hour>24) break;cin>>temperature;ost<<hour<<" "<<temperature<<endl;}system("pause");}

10.3

#include<iostream>#include<vector>#include<fstream>using namespace std;struct Reading{int hour;double temperature;Reading(int h,double t):hour(h),temperature(t){}};int main(){ifstream ist("E:\\raw_temps.txt");if(!ist) cout<<"打开文件失败！"<<endl;vector<Reading> temps;int hour,i;double temperature,sum;sum=0.0;while(ist>>hour>>temperature){temps.push_back(Reading(hour,temperature));}for(i=0;i<temps.size();i++){sum=sum+temps[i].temperature;}sum=sum/temps.size();cout<<"平均值为： "<<sum<<endl;system("pause");}

10.11

/*************************先找出文本中所有空格的的位置，再逐个判断文本头与第一个空格之间、空格与空格之间、最后一个空格和文本末之间是否是整数。*************************/#include<iostream>#include<fstream>#include<vector>#include<math.h>using namespace std;int main(){ifstream ist("E:\\text.txt");if(!ist) cout<<"打开文件失败！"<<endl;vector<char> ch;vector<int> space;char temp;int i,n,flag=0,num=0,sum=0;while((temp=ist.get())!=EOF) ch.push_back(temp);space.push_back(0);for(i=0;i<ch.size();i++)//找空格{if(ch[i]==' ') space.push_back(i);}space.push_back(ch.size());for(n=0;n<space.size()-1;n++)//判断是否为整数{for(i=space[n]+1;i<space[n+1];i++){num +=(ch[i]-48)*pow(10.0,(space[n+1]-i-1));if(ch[i]<'0'||ch[i]>'9') flag=1;if(flag==1){flag=0;num=0;break;}}sum +=num;}cout<<sum<<endl;system("pause");}

11.1

#include<iostream>#include<fstream>using namespace std;int main(){ifstream ist("E://C++_excise/11.1/input.txt");if(!ist) cout<<"can't open file!"<<endl;ofstream ost("E://C++_excise/11.1/output.txt");if(!ost) cout<<"can't creat file!"<<endl;char ch;while(ist.get(ch)){if(isalpha(ch)) ch=tolower(ch);ost<<ch;}ist.close();ost.close();}

11.10

#include<iostream>#include<string>#include<vector>#include<sstream>using namespace std;vector<string> split(const string& s,const string& w){vector<string> v;string st;istringstream is(s);while(is>>st){if(st!=w) v.push_back(st);}return v;}int main(){string s="she is a girl, but I'm not!",w="is";vector<string> v;v=split(s,w);for(int i=0;i<v.size();i++){cout<<v[i]<<endl;}system("pause");}

11.15

#include<iostream>#include<vector>#include<algorithm>#include<fstream>using namespace std;int main(){ifstream ist("E://C++_excise/11.15/input.txt");if(!ist) cout<<"can't open file!"<<endl;int i,k,n=1;vector<int> v;while(ist>>i){v.push_back(i);}sort(v.begin(),v.end());for(i=0;i<v.size();i++){for(k=i+1;k<v.size();k++){if(v[i]==v[k]) n++;else break;}cout<<v[i];if(n==1) cout<<endl;else cout<<'\t'<<n<<endl;n=1;i=k-1;}system("pause");}

0 0