CODEWITHSUNDEEP
c++stringchar
BlackM
BlackM

Reputation: 4071

Strings to Char in C++ Issues

I have this code:

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);

I just want to convert these 3 strings in one char*. I know my code is totaly wrong but I test a lot of things through google. Can somebody help me please?

Upvotes: 0

Views: 1198

Answers (3)

Alok Save
Alok Save

Reputation: 206656

You simply need to use strings::c_str()

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

If you need to get the string data in a char* and not const char * then you need to copy it as such: 

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;

Upvotes: 3

Luchian Grigore
Luchian Grigore

Reputation: 258698

You can't directly convert a string to a char*.

If a const char* is suitable, you can use string::c_str().

Otherwise, you need to copy the contents of the string to a pre-allocated char array.

Upvotes: 1

tune2fs
tune2fs

Reputation: 7705

Why do you need to have a *char. I would concatonate everything in final. If you need a *char you can acchieve this by calling:

 final.c_str();

If you want to use char. Make sure that you reserve enough memory:

 i=final.size()+1; 
 char *pp = new char[i];

Upvotes: 1

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