字符串操作 C++

Question

我需要做一些功能，但我不知道如何。

1. 連接兩個字符串，輸入位置並從字符串中的位置輸出字符

示例：s1=first，s2=second； s1+s2=firstsecond，pos=3,7,10，輸出=ren

這是我的一個位置的代碼，但我不知道如何制作多個位置，主要問題是如何限制位置的輸入：

s=s1+s2;
cin>>pos;
cout<<s[pos-1];

2. 在字符串中定義元音並用字符串替換該元音

示例：s=firstsecondthird，元音=i，str=EXA，輸出=fEXArstsecondthEXArd

這就是我所知道的，我不知道如何用 string(str) 替換元音

cin>>vowel;
if(check is defined character vowel)
{
   cin>>str;
   .
   .
   .
}

謝謝

Answer 1

抓住！ :)

#include <iostream>
#include <string>
#include <cstring>

int main() 
{
    std::cout << "Enter first string: ";

    std::string s1;
    std::cin >> s1;

    std::cout << "Enter second string: ";

    std::string s2;
    std::cin >> s2;

    s1 += s2;

    std::cout << "The joined string is " << s1 << std::endl;

    std::cout << "Enter several positions in the joined string (0-stop): ";

    std::string s3;
    std::string::size_type pos;

    while ( std::cin >> pos && pos != 0 )
    {
        if ( --pos < s1.size() ) s3 += s1[pos];
    }

    std::cout << "You have selected the following letters " << s3 << std::endl;

    const char *vowels = "aeiou";
    char c;

    do
    {
        c = '\0';
        std::cout << "Enter a vowel: ";
    } while ( std::cin >> c && !std::strchr( vowels, c ) );

    if ( c != '\0' )
    {
        for ( auto pos = s1.find( c, 0 ); 
              pos != std::string::npos; 
              pos = s1.find( c, pos ) )
        {
            const char *t = "EXA";
            const size_t n = 3;

            s1.replace( pos, 1, t );
            pos += n;
        }

        std::cout << "Now the joined string looks like " << s1 << std::endl;
    }       

    return 0;
}

如果進入

first
second
3 7 10 0
i

那么程序輸出將是

Enter first string: first
Enter second string: second
The joined string is firstsecond
Enter several positions in the joined string (0-stop): 3 7 10 0
You have selected the following letters ren
Enter a vowel: i
Now the joined string looks like fEXArstsecond

您可以將其用作出色程序的模板。:)