c++ 文本操作多种方法

文章目录

• ​​1、二进制文件流​​
• ​​2、直接文本方式​​

1、二进制文件流

#include <iostream>
#include <fstream>
#include <vector>
#define p "/home/barry/CLionProjects/temp/t.txt"
#define path "/home/barry/CLionProjects/temp/file1.txt"
#define path2 "/home/barry/CLionProjects/temp/file2.dat"

using  namespace std;

template<class T>
void serialize(ofstream& stream, T&x){
    stream.write((char*)&x, sizeof(T));
}

template <class T> // 基本类型-读
void de_serialize(ifstream& stream, T& x)  //读
{
    stream.read((char*)&x, sizeof(T));
}

void serialize(ofstream& stream, string& str)
{
    int len = str.length();
    stream.write((char*)&len, sizeof(int));
    stream.write(str.c_str(), len); //str.c_str()返回该字符串的首字符地址
}

//std::string  读
void de_serialize(ifstream& stream, string& str)
{
    int len;
    stream.read((char*)&len, sizeof(int));//读取字符串长度值
    str.resize(len); //调整字符串str的长度为len
    char x;
    for (int i = 0; i < len; i++)
    {
        stream.read(&x, sizeof(char));
        str[i] = x;
    }
}


class Student
{
    string stu_no;
    string name;
    int age;
public:
    Student(){};
    Student(string _st, string _na,int _ag){
        stu_no = _st; name = _na; age = _ag;
    }
    void display(){
        cout << stu_no << " " << name << " " << age << endl;
    }

    string get_stu_no(){ return stu_no; }
    string get_name(){ return name; }
    int get_age(){ return age; }
    friend void save(ofstream&stream, Student& student);
    friend void load(ifstream &stream, Student &student);
};

void save(ofstream&stream, Student& student){
    serialize(stream,student.stu_no);
    serialize(stream,student.name);
    serialize(stream, student.age);
}

void load(ifstream &stream, Student &student){
    de_serialize(stream,student.stu_no);
    de_serialize(stream,student.name);
    de_serialize(stream,student.age);

}


int main(){
    Student stu[3] = { Student("201101", "liming", 18), Student("201102", "zhangting", 18), Student("201103", "xiaobin", 19) };

    //写入文件
    ofstream out;
    out.open(path2,ios::binary|ios::app);
    if(!out){
        cout <<"error";
        abort();
    }
    for(int i = 0; i < 3; i++){
        save(out,stu[i]);
    }
    out.close();


    //读取文件
    Student stu2[3];
    ifstream in;
    in.open(path2,ios::binary);
    if(!in){
        cout << "error";
        abort();
    }

    Student s;
    while (in.peek() !=EOF){
        load(in,s);
        s.display();
    }
}

2、直接文本方式

#include <iostream>
#include <fstream>
#include <vector>
#define p "/home/barry/CLionProjects/temp/t.txt"
#define path "/home/barry/CLionProjects/temp/file1.txt"

using  namespace std;


//字符串分割函数
vector<string> split(string s,char c){
    vector<string> re;
    for(int i = 0; i < s.size(); i++){
        string t="";
        while(i<s.size()&&s[i]!=c){
            t+=s[i];
            i++;
        }
        re.push_back(t);
    }
    return re;
}

class Student
{
    string stu_no;
    string name;
    int age;
public:
    Student(){};
    Student(string _st, string _na,int _ag){
        stu_no = _st; name = _na; age = _ag;
    }
    void display(){
        cout << stu_no << " " << name << " " << age << endl;
    }

    string get_stu_no(){ return stu_no; }
    string get_name(){ return name; }
    int get_age(){ return age; }
};

void line_write(string s){
    ofstream outfile;
    outfile.open(path,ios::app);
    cout << "Writing to the file" << endl;
    outfile<<s.data();
    outfile.close();
}

void line_read(){
    string G[1000];
    int k = 0;

    char buffer[256];
    fstream out;
    out.open(path,ios::in);
    while(!out.eof())
    {

        out.getline(buffer,256,'\n');//getline(char *,int,char) 表示该行字符达到256个或遇到换行就结束
        G[k++] = buffer;
       // cout<<buffer<<endl;
    }


    out.close();
    vector<string> re[1000];
    for(int i = 0; i < k; i++){
        re[i] = split(G[i],' ');
    }

    for(int i = 0; i < k; i++){
        Student t(re[i][0],re[i][1],stoi(re[i][2]));
        t.display();
    }
}
int main(){
    Student stu[3] = { Student("201101", "liming", 18), Student("201102", "zhangting", 18), Student("201103", "xiaobin", 19) };

    //写入文本
    for (int i = 0; i < 3; i++){
        string str = "";
        str = stu[i].get_stu_no()+" "+stu[i].get_name()+" "+ to_string(stu[i].get_age())+"\n";
        line_write(str);
    }
    //读取文本
    line_read();
}

结果

使用了fstream与ofstream对文件file1进行读写操作。在写入文件时，student对象的不同属性之间使用空格隔开写入文件，file1文件内容如下所示

在读取时，按行读取，并且使用vector split(string s, char c);对每行字符串进行按空格分割，得到的数据进行Student对象的生命，再调用student->display()函数展示数据即可。