如何在C ++的内置类中添加成员函数? [英] How can I add member functions in built-in classes in c++?

问题描述

我想向字符串类添加一个新的成员函数"charReplace".该功能将用一个字符替换所有出现的一个字符.所以我准备了一个示例代码.

I want to add a new member function "charReplace" to the string class. The function will replace all the occurances of one character with another character. So I prepared a sample code.

#include <iostream>
#include <string>

std::string string::charReplace(char c1, char c2) { //error in this line
    while(this->find(c1) != std::string::npos) {
        int c1pos = this->find(c1); //find the position of c1
        this->replace(c1pos, 1, c2); //replace c1 with c2
    }
    return *this;
}

int main() {
    std::string s = "sample string";

    s.charReplace('s', 'm') /* replace all s with m */

    std::cout << s << std::endl;
}

但是它不起作用.编译时在第4行出现以下错误.

But it is not working. I am getting the following error in line 4 while compiling.

错误:字符串"未命名类型

error: 'string' does not name a type

我知道通过创建非成员函数很容易获得相同的结果.但是我想使用成员函数来做到这一点.那么，有没有办法在c ++中做到这一点?

I know that it is quite easy to get the same result by creating a non-member function. But I want to do it using a member function. So, is there a way to do this in c++?

P.S.我还是C ++新手.我已经使用几个月了.因此，请尝试使您的答案易于理解.

P.S. I am still new with c++. I have been using it for a few months only. So, please try to make your answer easy to understand.

推荐答案

您不能.这是C ++，而不是JavaScript(您可以在其中编写任何类的原型).

you can't. this is C++, not JavaScript (where you can prototype any classes).

您的选择是:

1. 继承力
2. 组成
3. 独立功能

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