c++学习-字符串

时间：2023-03-10 03:28:09
c++学习-字符串

字符数组和 string类型比较的区别

#include<iostream>

#include<string>

using namespace std;

class area{

public:

    area(){ cout << "gouzao:" <<endl; }

    area(int i){ this->i = i; cout << "gouzao:" << i << endl; }

    area(int w, int h){ this->w = w; this->h = h; cout << "gouzao" << endl; }

    ~area(){ cout << "xigou "<<i << endl; }

    int get()

    {

        return w*h;

    }

    void set(int w, int h)

    {

        this->w = w;

        this->h = h;

    }

private:

    int w;

    int h;

    int i;

};

int main()

{

    //char 数组做比较需要 strcmp

    //char a[] = "ab";

    //char b[] = "ab";

    //cout << (a==b) << endl;//不相等，比较的是两个地址

    //cout << strcmp(a, b) << endl;

    //cout << strcmp(a, "ab") << endl;

    string a = "ab";

    cout << (a == "ab") << endl; //wright

    return 0;

}

赋值比较：

int main()

{

    char ch1[10] = "ab";

    char ch2[10] = "cd";

    //ch1 = ch2;  //错误

    strcpy(ch1, ch2);

    string ch3 = "ab";

    string ch4 = "cd";

    ch3 = ch4;

    cout << ch3 << endl;

    cout << ch4 << endl;

    return 0;

}

字符串赋值：

#include<iostream>

#include<string>

using namespace std;

class area{

public:

    area(){ cout << "gouzao:" <<endl; }

    area(int i){ this->i = i; cout << "gouzao:" << i << endl; }

    area(int w, int h){ this->w = w; this->h = h; cout << "gouzao" << endl; }

    ~area(){ cout << "xigou "<<i << endl; }

    int get()

    {

        return w*h;

    }

    void set(int w, int h)

    {

        this->w = w;

        this->h = h;

    }

private:

    int w;

    int h;

    int i;

};

int main()

{

    //char ch1[10] = "ab";

    //char ch2[10] = "cd";

    ////ch1 = ch2;  //错误

    //strcpy(ch1, ch2);

    string ch3 = "ab";

    string ch4 = "cd";

    ch3 = ch4;

    ch3.assign(ch4,,); //部分元素赋值给ch3

    cout << ch3 << endl;

    cout << ch4 << endl;

    return ;

}

字符串合并：

int main()

{

    string ch1 = "ab";

    string ch2 = "cd";

    ch1 = ch1 + ch2;

    cout << ch1 << endl;

    cout << ch2 << endl;

    return ;

}

计算长度：

int main()

{

    string ch1 = "ab";

    string ch2 = "cd";

    ch1 = ch1 + ch2;

    cout << ch1 << endl;

    cout << ch2 << endl;

    //计算字符长度

    cout << strlen(ch1.c_str()) << endl;

    cout << ch1.size() << endl;

    cout << ch1.length() << endl;

    return ;

}

字符串部分合并：

int main()

{

    //char ch3[10] = "ab";

    //char ch4[10] = "abcdefg";

    //strncat(ch3, ch4, 3);

    //cout << ch3 << endl;

    string ch1 = "ab";

    string ch2 = "cdefg";

    ch1.append(ch2, ,);

    cout << ch1 << endl;

    return ;

}

字符串替换：

int main()

{

    //char ch3[10] = "ab";

    //char ch4[10] = "abcdefg";

    //strncpy(ch3, ch4, 3);

    //cout << ch3 << endl;

    string ch1 = "ab";

    string ch2 = "cdefg";

    char ch5[] = "cdefg";

    char ch6 = 'A';

    //ch1.replace(0,1,ch2, 2,2);

    //ch1.replace(0, 1, ch5, 2, 2);//支持char型数组

    //ch1.replace(0, 1, 2, ch6);//支持char 字符

    cout << ch1 << endl;

    return ;

}

字符串拷贝：

int main()

{

    char ch3[] = "abffffff";

    char ch4[] = "abcdefg";

    memmove(ch3, ch4, );

    cout << ch3 << endl;

    string ch1 = "abcdefghkjklmn";

    char ch5[] = "cdefg";

    cout << ch5 << endl;

    ch1.copy(ch5,,);

    cout << ch5 << endl;

    return ;

}

字符串插入：

int main()

{

    string str1 = "abcdefg";

    string str2 = "abc"; 

    str1.insert(,str2, ,);

    cout << str1 << endl;

    return ;

}

字符串删除：

int main()

{

    string str1 = "abcdefg";

    str1.erase(,);

    cout << str1 << endl;

    return ;

}

删除字符串：

int main()

{

    string str1 = "abcdefg";

    str1.erase(,);

    cout << str1 << endl;

    str1.erase();//第二个以后全部删除

    cout << str1 << endl;

    str1.erase();//清空一个字符串

    cout << str1 << endl;

    return ;

}

字符串查找：

int main()

{

    char ch1[] = "hello world!";

    char *p, c = '';

    p = strchr(ch1, c);//返回找到的w字符的地址，找不到则返回空指针

    if (p)

    {

        cout << p << endl;

        cout << p - ch1 << endl; //计算找到的字符的下标

    }

    return ;

}
int main()

{

    string str1("abcdefg");

    int f = str1.find('b', ); //从第一个字符开始查找

    if (f == string::npos)

    {

        cout << "not find " << endl;

    }

    cout << f << endl;

    f = str1.find_first_not_of('b', ); //查找第一个不是b的字符

    cout << f << endl;

    f = str1.find_last_of('b'); //查找最后一个b的位置

    cout << (int)string::npos << endl;

    return ;

}

判断字符串是否为空：

int main()

{

    string s1 = "";

    if (s1.empty())

    {

        cout << "empty" << endl;

    }else{

        cout << "not empty" << endl;

    }

    return ;

}

字符串交换：

int main()

{

    char ch1[] = "ofru";

    char ch2[] = "";

    swap(ch1,ch2);

    cout << ch1 << endl;

    cout << ch2 << endl;

    string str1 = "ab";

    string str2 = "";

    str1.swap(str2);

    cout << str1 << endl;

    cout << str2 << endl;

    return ;

}

string字符串转char型

int main()

{

    string str1 = "abcde";

    const char *p;

    p = str1.c_str();

    cout << p << endl;

    return ;

}

字符串传参：

int get_length(const char *p)

//int get_length(const char p[])

{

    int count = ;

    while (*p)

    {

        count++;

        p++;

    }

    return count;

}

int main()

{

    char a[] = "abc";

    char *p = "defg";

    cout << get_length(a) << endl;

    cout << get_length(p) << endl;

    return ;

}

字符串函数返回：

char *get(const char *str)

{

    char *p = new char[strlen(p) +];

    strcpy(p, str);

    return p;

}

int main()

{

    char a[] = "abc";

    char *p = get(a);

    cout << p << endl;

    char *p2 = get("abc");

    cout << p << endl;

    char *p3 = "abc";

    char *p4 = get(p3);

    cout << p4 << endl;

    delete[]p;

    return ;

}

结构体：

#include<iostream>

#include<string>

using namespace std;

struct man{

public:

    int age;

    char *name;

};

int main()

{

    struct man one={

        ,

        "中国"

    };

    cout << one.age << endl;

    cout <<one.name<< endl;

    return ;

}

结构体与构造函数：

#include<iostream>

#include<string>

using namespace std;

struct man{

    man(int c_age);

//public:

    int age;

    char *name;

    string name1;

};

man::man(int c_age)

{

    age = c_age;

}

int main()

{

    man one();

    cout << one.age << endl;

    return ;

}

结构体赋值：

#include<iostream>

#include<string>

using namespace std;

struct man{

    int age;

    char *name;

    string name1;

};

int main()

{

    man one = {

        , "one", "one1"

    };

    man two = {

        , "two", "two1"

    };

    one = two;

    cout << one.age << endl;

    cout << one.name << endl;

    cout << one.name1 << endl;

    return ;

}

结构体与函数：

#include<iostream>

#include<string>

using namespace std;

struct time{

    int hour;

    int minute;

};

const int perhour = ;

time sum(time t1, time t2);

int main()

{

    time t1 = {,};

    time t2 = { ,  };

    time total = sum(t1,t2);

    cout << total.hour << endl;

    cout << total.minute << endl;

    return ;

}

time sum(time t1, time t2)

{

    time total;

    total.minute = (t1.minute + t2.minute) % perhour;

    total.hour = t1.hour + t2.hour + ((t1.minute + t2.minute) / perhour); 

    return total;

}

指针方式返回：

#include<iostream>

#include<string>

using namespace std;

struct time{

    int hour;

    int minute;

};

const int perhour = ;

time *sum(const time &t1, const time &t2);

int main()

{

    time t1 = {,};

    time t2 = { ,  };

    time *total = sum(t1,t2);

    cout << total->hour << endl;

    cout << total->minute << endl;

    return ;

}

time *sum(const time &t1, const time &t2)

{

    time *total = new time;

    total->minute = (t1.minute + t2.minute) % perhour;

    total->hour = t1.hour + t2.hour + ((t1.minute + t2.minute) / perhour);

　　delete total;

    return total;

}

引用方式传递返回：

#include<iostream>

#include<string>

using namespace std;

const string &show(const string &str);

int main()

{

    string str1 = "abc";

    string str2 = show(str1);

    cout << str2 << endl;

    return ;

}

const string &show(const string &str)

{

    return str;

}

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