如何在 C++ 中将 std::string 转换为 const char
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How to convert std::string to const char in C++
提问by PritishC
I tried to research this for a bit and I can't figure out the problem
我试着研究了一下，但我无法弄清楚问题所在
Here's the code:
这是代码：
#include <iostream>
#include <stdlib.h>
#include <string>
void choose();
void newuser();
void admuse();
using namespace std;
string x;
string z;
string w;
void CreNeAcc(){
cout << "Enter User Name for your new account\n";
getline(cin, x);
cout << "Enter Password for your new account\n";
getline(cin, z);
cout << "Would you like the account to be admin?\n";
cout << "Yes = Y, No = N\n";
getline(cin, w);
choose();
}
void choose(){
if(w == "Y"){
newuser();
admuse();
}else if(w == "N"){
newuser();
}else{
cout << "Invalide Command\n";
}
}
void newuser(){
const char* Letter_x = x.c_str();
char command [100] = "net user /add ";
strcat(command, x); //This is where I get the error
strcat(command, " ");
strcat(commad, z);
system(command);
}
void admuse(){
system("new localgroup administrators " << x << " /add")
}
also the error its giving me is:
它给我的错误也是：
cannot convert 'std::string {aka std::basic_string<char>}' to 'const char*' for argument '2' to 'char* strcat(char*, const char*)'|
回答by Matt Reynolds
You have to use c_str()(see here). It's implemented by simply apending it to your std::string, like so:
您必须使用c_str()（请参阅此处）。它是通过简单地将它附加到您的 来实现的std::string，如下所示：
string myFavFruit = "Pineapple"
const char* foo = myFavFruit.c_str();
strcat(command, foo);
Actually, you have everything there you're just not using your const char*variable in the strcat()'s arguments. You define Letter_x, but then use xin the function instead. Rewrite your newuser()as follows:
实际上，您拥有一切，只是没有const char*在strcat()的参数中使用变量。您定义Letter_x，然后x在函数中使用。重写你的newuser()如下：
void newuser(){
const char* Letter_x = x.c_str();
char command [100] = "net user /add ";
strcat(command, Letter_x); //Here, use 'Letter_x' instead of 'x'
strcat(command, " ");
strcat(command, z); //You will also need to do your 'c_str()' conversion on z before you can use it here, otherwise you'll have the same error as before.
system(command);
}
Lastly, you can avoid all this because you can append strings simply using the +=operator (see here). Try this:
最后，您可以避免所有这些，因为您只需使用+=运算符即可附加字符串（请参阅此处）。尝试这个：
string command = "net user /add ";
command += x;
command += " ";
command += z;
回答by Pawe? Stawarz
In order to convert a stringinto an const char*use c_str().
为了将 astring转换为const char*use c_str()。
On a side note tho:why are you using strcatin the first place? You can concatenate strings with the operator+.
附带说明一下：您strcat首先为什么要使用？您可以将字符串与operator+.
string a = "try", b = " this";
string c = a+b; // "try this"
回答by PritishC
You might be looking for this: How to convert a char* pointer into a C++ string?
您可能正在寻找：如何将 char* 指针转换为 C++ 字符串？
According to the link, you may use c_str()to return a pointer to a null terminated char array version of your string.
根据链接，您可以使用c_str()返回指向字符串的空终止字符数组版本的指针。
