C++中string的替换/删除/增加子串

淩亂°似流年 2022-05-21 13:13 306阅读 0赞

## 编写函数将string里的特定子字符串替换为新值 ##

#include"stdafx.h"
    #include<iostream>
    #include<string>
    //#include "ProgramRunClock.h"
    //#include<vector>
    //#include<list>
    //#include<time.h>
    using namespace std;
    /*void replaceVal(string &s,const string oldVal,const string newVal)
    {//使用find方法的，find找子串返回一个下标值，相同的第一个字符的位置
        if(*(s.end()-1)!='.')s.push_back('.');
        size_t index = s.find(oldVal);
        while (index!= s.npos)
        {
            s.erase(index, oldVal.size());
            s.insert(index,newVal);
            index = s.find(oldVal);
        }
    
    }*/
    
    /*void replaceVal(string &s,const string oldVal,const string newVal)
    {
        string::size_type sLength = s.size(), oldLength = oldVal.size(), newLength = newVal.size();
        if (s[sLength - 1] != '.')s.push_back('.');
        for (size_t index = 0; index != sLength; index++)
        {//使用下标和substr切割子串比较的方法
            if (s.substr(index, oldLength) == oldVal)
            {
                s.erase(index,oldLength);
                s.insert(index,newVal);//插入字符串需要size_t类型参数
            }
        }
    
    }*/
    
    /*void replaceVal(string &s, const string oldVal, const string newVal)
    {
        if (*(s.end() - 1) != '.')s.push_back('.');
        string::iterator itr;
    
        for (itr = s.begin(); itr != s.end()-oldVal.size()-1; itr++)
        {//迭代器与构造临时比较字符串
            string temp(itr,itr+oldVal.size());
            if (temp == oldVal)
            {
                s.erase(itr,itr+oldVal.size());
                for (auto c : newVal)
                {//若使用迭代器做参数，insert只能逐个字符插入
                    itr = s.insert(itr,c);
                    advance(itr, 1);
                }
            }
        }
    }*/
    
    void replaceVal(string &s, const string oldVal, const string newVal)
    {
        string::size_type sLength = s.size(), oldLength = oldVal.size();
        if (s[sLength - 1] != '.')s.push_back('.');
        for (size_t index = 0; index != sLength; index++)
        {//下标及replace方法
            if (s.substr(index, oldLength)==oldVal)
            {//replace接收一个起始下标值，一个长度范围，一个新串
                s.replace(index, oldLength, newVal);
            }
        }
    }
    int main(int argc, char **argv) {
        string str_a{
       "some people enjoy swimming, \nsome people wanna learn to swim,\nand some other people hate swimming"};
        cout << str_a << endl;
        string a, b;
        cout << "旧的词: ";
        cin >> a;
        cout << "新的词: ";
        cin >> b;
        replaceVal(str_a,a,b);
        cout << "更改后的句子"<<endl<<str_a << endl;
        return 0;
    }

## 给人名string加前/后缀 ##

#include"stdafx.h"
    #include<iostream>
    #include<string>
    //#include "ProgramRunClock.h"
    //#include<vector>
    //#include<list>
    //#include<time.h>
    using namespace std;
    /*string NameAdd(string base, const string &front, const string &back) { //用迭代器、append、insert修改 base.append(" "+back); string::iterator itr = base.begin(); for (auto c : front) { itr = base.insert(itr,c); advance(itr, 1); } return base; }*/
    string NameAdd(string base, const string &front, const string &back)
    {
        //使用位置、长度、insert
        base.insert(base.size(),back);
        base.insert(0, front);
        return base;
    }
    int main(int argc, char **argv) {
        string Namebase,Addfront,Addback;
        cout << "名字主体: ";
        cin >> Namebase;
        cout << "要添加的前缀: ";
        cin >> Addfront;
        cout << "要添加的后缀: ";
        cin >> Addback;
        string NewName = NameAdd(Namebase, Addfront, Addback);
        cout << "旧名字: " << Namebase << endl;
        cout <<"新名字: "<< NewName << endl;
        return 0;
    }