c++ string類基本使用

• 初始化用法

#include <iostream>
#include "string"
using namespace std;
void main()
{
    string m1 = "陳培昌";
    string m2("付高峰");
    string m3 = m2;
    cout<<"m1:"<<m1<< endl;
    cout<< "m2:" << m2 << endl;
    cout<< "m3:" << m3 << endl;
}

• 三種遍歷方式

void main()
{
    string chroums = "Deep love is a burning fire Stay";
    //方法一：數組遍歷
    int  i;
    for (i=0;i<chroums.length();i++)
    {
        cout << chroums[i];
    }
    cout<<endl << "==============================" << endl;
    //方法二：迭代器
    for (string::iterator it = chroums.begin(); it != chroums.end(); it++)
    {
        cout << *it;
    }
    string myequal(30, '*');//一次性生成30個*
    cout<<endl<<myequal << endl;
    //方法三：at()
    for (i = 0; i < chroums.length(); i++)
    {
        cout << chroums.at(i);
    }
    string anotherequal(40, '$');
    cout << endl << anotherequal << endl;
}

輸出結果：

 

•  選擇at()方法遍歷的好處----可以捕捉異常，注意示例中，故意越界訪問

void main()
{
    string chroums = "Deep love is a burning fire Stay";
    string myequal(30, '*');//一次性生成30個*
    cout << endl << myequal << endl;
    //方法三：at()
    int i = 0;
    try
    {
        for (i = 0; i < chroums.length() + 3; i++)
        {
            cout << chroums.at(i);
        }
    }
    catch (...)
    {
        cout << endl;
        cout << "crisis happend" << endl;
    }
    system("pause");
}

輸出結果：

 

•  而選用其他方式遍歷，盡管采取措施捕捉異常，仍舊無法制止錯誤

#include <iostream>
#include "string"
using namespace std;
void main()
{
    string chroums = "Deep love is a burning fire Stay";
    
    //方法二：迭代器
    try
    {
        for (string::iterator it = chroums.begin(); it != chroums.end()+3; it++)
        {
            cout << *it;
        }
    }
    catch (...)
    {
        cout << "crisis happend" << endl;
    }
    
    
    string anotherequal(40, '$');
    cout << endl << anotherequal << endl;
}

輸出結果：

 

• 查找目標字符串位置

void main()
{
    string mywords = "Brother Louie, Louie, Louie";
    size_t step3 = mywords.find("Louie",0);//size_t是C語言int類型的一種引用
    cout <<"在字符串索引處"<< step3<<"找到目標字符串" << endl;
}

輸出結果：

 

 改進：持續查找(偏移量不等於字符串的末尾)

 

void main()
{
    string mywords = "Brother Louie, Louie, Louie";
    size_t step3 = mywords.find("Louie",0);//size_t是偏移量，在C語言中是int類型的引用
    while (step3!=string::npos)
    {
        cout << "在字符串索引處" << step3 << "找到目標字符串" << endl;
        step3 = step3 + 1;
        step3 = mywords.find("Louie", step3);
    }
}

輸出結果：

• 替換

void main()
{
    string mywords = "徐曉冬卷了一只烤鴨餅，兀自咀嚼了起來。而陳培昌盛了一勺湯，品着陷入了沉思";
    mywords.replace(0,6,"付高峰");
    cout << mywords <<endl;
}

輸出結果：

 

• 特別位置上的替換

void main()
{
    string mywords = "付高峰卷了一只烤鴨餅，兀自咀嚼了起來。而陳培昌盛了一勺湯，品着陷入了沉思";
    mywords.replace(0,6,"徐曉冬");
    size_t cpc = mywords.find("陳培昌",0);
    mywords.replace(cpc,6,"吳子龍");
    cout << mywords <<endl;
}

 輸出結果：

• 截斷

void main()
{
    string mywords = "Brother Louie, Louie, Louie";
    //size_t t = mywords.find("烤羊腿",0);
    string::iterator it = find(mywords.begin(),mywords.end(),'L');
    if (it!= mywords.end())
    {
        mywords.erase(it);
    }
    cout << mywords << endl;
    //截斷字符串erase()
}

輸出：