c++ - 用一个int乘以一个字符串

声明:本页面是StackOverFlow热门问题的中英对照翻译,遵循CC BY-SA 4.0协议,如果您需要使用它,必须同样遵循CC BY-SA许可,注明原文地址和作者信息,同时你必须将它归于原作者(不是我):StackOverFlow 原文地址: http://stackoverflow.com/questions/11843226/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me): StackOverFlow

提示:将鼠标放在中文语句上可以显示对应的英文。显示中英文
时间:2020-08-27 15:37:26  来源:igfitidea点击:

Multiplying a string by an int in c++

c++stringintegercoutmultiplication

提问by user1575615

What do I have to do so that when I

我该怎么做才能当我

string s = ".";

If I do

如果我做

cout << s * 2;

Will it be the same as

会不会和

cout << "..";

?

?

回答by JRG

std::string has a constructor of the form

std::string 具有以下形式的构造函数

std::string(size_type count, char c);

that will repeat the character. For example

这将重复该字符。例如

#include <iostream>

int main() {
   std::string stuff(2, '.');
   std::cout << stuff << std::endl;
   return 0;
}

will output

会输出

..

回答by ForEveR

No, std::stringhas no operator *. You can add (char, string) to other string. Look at this http://en.cppreference.com/w/cpp/string/basic_string

不,std::string没有operator *。您可以将 (char, string) 添加到其他字符串。看看这个http://en.cppreference.com/w/cpp/string/basic_string

And if you want this behaviour (no advice this) you can use something like this

如果你想要这种行为(没有建议),你可以使用这样的东西

#include <iostream>
#include <string>

template<typename Char, typename Traits, typename Allocator>
std::basic_string<Char, Traits, Allocator> operator *
(const std::basic_string<Char, Traits, Allocator> s, size_t n)
{
   std::basic_string<Char, Traits, Allocator> tmp = s;
   for (size_t i = 0; i < n; ++i)
   {
      tmp += s;
   }
   return tmp;
}

template<typename Char, typename Traits, typename Allocator>
std::basic_string<Char, Traits, Allocator> operator *
(size_t n, const std::basic_string<Char, Traits, Allocator>& s)
{
   return s * n;
}

int main()
{
   std::string s = "a";
   std::cout << s * 5 << std::endl;
   std::cout << 5 * s << std::endl;
   std::wstring ws = L"a";
   std::wcout << ws * 5 << std::endl;
   std::wcout << 5 * ws << std::endl;
}

http://liveworkspace.org/code/52f7877b88cd0fba4622fab885907313

http://liveworkspace.org/code/52f7877b88cd0fba4622fab885907313

回答by Ferruccio

There is no predefined *operator that will multiply a string by an int, but you can define your own:

没有*将字符串乘以 的预定义运算符int,但您可以定义自己的运算符:

#include <iostream>
#include <sstream>
#include <string>

using namespace std;

string operator*(const string& s, unsigned int n) {
    stringstream out;
    while (n--)
        out << s;
    return out.str();
}

string operator*(unsigned int n, const string& s) { return s * n; }

int main(int, char **) {
    string s = ".";
    cout << s * 3 << endl;
    cout << 3 * s << endl;
}

回答by huseyin tugrul buyukisik

Strings cannot be multiplied.

字符串不能相乘。

if s is a char

如果 s 是一个字符

'.'     //this has 46 ascii-code

then

然后

cout << (char)((int)s * 2);

will give you

会给你

'/'     //this has 92 ascii-code

回答by jcoder

They can't be multipled but I think you can write your own function to do this, something like -

它们不能相乘,但我认为您可以编写自己的函数来执行此操作,例如-

#include <iostream>
#include <string>

std::string operator*(std::string s, size_t count)
{
    std::string ret;
    for(size_t i = 0; i < count; ++i)
    {
        ret = ret + s;
    }
    return ret;
}


int main()
{
    std::string data = "+";
    std::cout << data * 10 << "\n";
}

It's probably not the best idea though, it will be very confusing to anyone looking at the code and not expecting this,

不过,这可能不是最好的主意,对于任何查看代码但不期望这一点的人来说,这将非常令人困惑,

回答by Sanjin Brus

You can do this:

你可以这样做:

#include <iostream>
using namespace std; 

int main() 
{  
string text,new_text;
int multiply_number;

cin>>text>>multiply_number;

/*First time in for loop:new_text=new_text+text
                         new_text=""+"your text"
                         new_text="your text"
  Secound time in for loop:new_text=new_text+text
                         new_text="your text"+"your text"
                         new_text="your textyour text"...n times */

for(int i=0;i<multiply_number;i++){

new_text+=text; 

}

cout<<new_text<<endl;    // endl="\n"

system ("pause");
return 0;       
} 

In python you can multiply string like this:

在python中,您可以像这样乘以字符串:

text="(Your text)"
print(text*200)