char *t;
int size = datalength[0];
datalength.erase(0);
t= new char[size];
for (int i=0;i<size;i++)
{
t=data[0];
data.erase(0);
}
return t;
vector not working
Author
here's the code with the problem
Is it really necessary that you delete the vector element after each copy? You could always copy each value and then just clear() the vector at the end.
and for this:
Shouldnt that be t = data?
Id be interested in seeing a bit more of how your code is structured, because im sure there must be a better way than to have to write code to perform that kind of function
and for this:
t=data[0];Shouldnt that be t = data?
Id be interested in seeing a bit more of how your code is structured, because im sure there must be a better way than to have to write code to perform that kind of function
Author
this is all the code:
the objective of it is to add a string to data with dat() and store the size of the string in datalength, then return the first string in data with readdata() and delete the space the string occupied.
std::vector<int> datalength;std::vector<char> data;int dat(const char *t){ if (strlen(t)==0) {return 0;} int size = strlen(t); for (int i=0;i<size;i++) {data.push_back(t);} datalength.push_back(size); return datalength[0];}char* readdata(void){ if (datalength.size()==0) { return ""; } char *t; int size = datalength[0]; datalength.erase(0); t= new char[size]; for (int i=0;i<size;i++) { t=data[0]; data.erase(0); } return t;}the objective of it is to add a string to data with dat() and store the size of the string in datalength, then return the first string in data with readdata() and delete the space the string occupied.
hmmm, why not just use std::string? And if you need to store lots of them just declare a single Vector<std::string>
Then if you need the length of the string, just use its length() function to return it. If you need to pass a char* to other functions, you can just call its c_str() function (which returns the same string as a char*)
Unless theres something im missing, i really cant see any reason for needing those kind of functions....
Then if you need the length of the string, just use its length() function to return it. If you need to pass a char* to other functions, you can just call its c_str() function (which returns the same string as a char*)
Unless theres something im missing, i really cant see any reason for needing those kind of functions....
Here's a few ways to do what you want. Note that I took out datalength in both versions:
#include <iostream>#include <vector>#include <string>std::vector< std::string > data;int dat( const char * t ) { // no need for datalength std::string s( t ); if( s.size() == 0 ) return 0; data.push_back( s ); return s.size();}char * const readdata() { // mixing C and C++ if( data.size() == 0 ) return 0; // return null if we have no strings char * c_string = new char[ data.front().size() ]; // destroy this later somehow ... :( copy( data.front().begin(), data.front().end(), c_string ); // copy string to buffer c_string[ data.front().size() ] = 0; // append null char data.erase( data.begin() ); // erase first string return c_string;}std::string readdata2() { // the C++ way if( data.size() == 0 ) return ""; // no dealing with null pointers here std::string s( data.front() ); // copy the first string data.erase( data.begin() ); // erase the first string return s;}int main() { // add some strings including null string std::cout << "size: " << dat( "Hello, vector!" ) << std::endl; std::cout << "size: " << dat( "Hello, string!" ) << std::endl; std::cout << "size: " << dat( "Hello, STL!" ) << std::endl; std::cout << "size: " << dat( "" ) << std::endl; // read some strings using both methods std::cout << "string: \"" << readdata() << "\"" << std::endl; // <- leaking all kinds std::cout << "string: \"" << readdata() << "\"" << std::endl; // <- of memory std::cout << "string: \"" << readdata2() << "\"" << std::endl; std::cout << "string: \"" << readdata2() << "\"" << std::endl; // <- readdata() would crash here return 0;}
It's not mine. For some reason Code::Blocks is very inconsistent with tabs/spaces. It's something I deal with though. For the record, I tab @ 3, and (try to) convert those to spaces.
Hello,
You can't use the erase() method like this. The argument of erase() is an iterator, not an indexed position - in your case, it should be datalength.begin(). As Sava, I also suggest you to try to limit the use of erase(). Stylin's C++ version is quite good :)
Regards,
Quote:Original post by flounder
here's the code with the problem
(** snip code **)
the code works fine except for this part. datalength holds the size of the string and is the correct size. what i've been trying to do is load each character of the vector into the string while deleting the vector, and no i cannot just return the vector. can anyone point out anything wrong?
You can't use the erase() method like this. The argument of erase() is an iterator, not an indexed position - in your case, it should be datalength.begin(). As Sava, I also suggest you to try to limit the use of erase(). Stylin's C++ version is quite good :)
Regards,
This topic is closed to new replies.
Advertisement
Popular Topics
Advertisement
