c++ - C++ 问题中的字符串转字符

Question

我有这个代码:

string username;
string node;
string at;
string final;

struct passwd* user_info = getpwnam("mike"); 
struct utsname uts;

uname(&uts);

username = user_info->pw_name;
node = uts.nodename;
at = "@";
final = username + at +node;
i=strlen(final[0]);
char *pp = new char[i];
strcpy(pp,final);

    fputs(pp, stdout);

我只想将这 3 个 strings 转换成一个 char*。我知道我的代码完全错误，但我通过谷歌测试了很多东西。有人可以帮帮我吗？

Answer 1

您只需要使用 strings::c_str()

string final;
const char *pp  = final.c_str();

如果您需要获取 char* 而不是 const char * 中的字符串数据，那么您需要按如下方式复制:

std::string final;

//Allocate pointer large enough to hold the string data +  NULL
char *pp = new char[final.size() + 1];

//Use Standard lib algorithm to copy string data to allocated buffer
std::copy(final.begin(), final.end(), pp);

//Null terminate after copying it
pp[final.size()] = '\0'; 

//Make use of the char *


//delete the allocated memory after use, notice delete []
delete []pp;