problem in a very simple code

[Aris]

Hi all!
this is the code:
#include <iostream.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

void MyFunction(char *B[])
{
cout<<sizeof(B)<<endl; //(1)
}

int main()
{
char* B[]={"1","2","we"};
MyFunction(B);
cout<<sizeof(B)<<endl;//(2)

system("PAUSE");
return 0;
}

and this is the problem :
in the (1) cout I get the answer :4
and in the (2) cout I get 12!
How can I handle this please?

[Gianni Mariani]

Aris wrote:

Hi all!
this is the code:
#include <iostream.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

void MyFunction(char *B[])
{
cout<<sizeof(B)<<endl; //(1)
}

int main()
{
char* B[]={"1","2","we"};
MyFunction(B);
cout<<sizeof(B)<<endl;//(2)

system("PAUSE");
return 0;
}

and this is the problem :
in the (1) cout I get the answer :4
and in the (2) cout I get 12!
How can I handle this please?

This should be in the FAQ - but here is a previous thread on the topic.

http://groups.google.com/group/comp....bfe04d1eaf64a8

Options are:

a) pass a length
b) use a template
c) do without
Example of a)
void MyFunction(char *B[], int length )
{
cout<<sizeof(*B)*length<<endl; //(1)
}

Example of b)

template <int N>
void MyFunction(char *(&B)[N])
{
cout<<sizeof(B)<<endl; //(1)
}

[BobR]

Aris wrote in message ...

Hi all!
this is the code:
#include <iostream.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

void MyFunction(char *B[]){
cout<<sizeof(B)<<endl; //(1)
}

int main(){
char* B[]={"1","2","we"};
MyFunction(B);
cout<<sizeof(B)<<endl;//(2)

system("PAUSE");
return 0;
}

and this is the problem :
in the (1) cout I get the answer :4
and in the (2) cout I get 12!
How can I handle this please?

By using C++?

#include <iostream>
#include <ostream> // for endl.
// #include <cstdlib> // #include <cstdio>
#include <string>
#include <vector>

void MyFunction( std::vector<std::string> const &Bstr ){
std::cout<<"in "<<__FUNCTION__<<" size="<<Bstr.size()
<<std::endl; //(1)
for(size_t i(0); i< Bstr.size(); ++i){
std::cout<<"Bstr.at("<<i<<")"<<Bstr.at(i)<<std::en dl;
}
}

int main(){
std::string B[]={"1","2","we"};
std::vector<std::string> vBstr;
std::copy(B, B+(sizeof B/sizeof *B), std::back_inserter(vBstr));
MyFunction( vBstr );
std::cout<<"string array size = "<<sizeof B/sizeof *B<<endl;//(2)

system("PAUSE");
return 0;
}

--
Bob R
POVrookie

[red floyd]

BobR wrote:

Aris wrote in message ...

[redacted]

By using C++?

[redacted]
void MyFunction( std::vector<std::string> const &Bstr ){
std::cout<<"in "<<__FUNCTION__<<" size="<<Bstr.size()
<<std::endl; //(1)
If you're going to be pedantic to the OP, then try using Standard C++
yourself. __FUNCTION__ is a g++-ism, and is not part of the Standard.
system("PAUSE");
return 0;
}

--
Bob R
POVrookie

[BobR]

red floyd wrote in message ...

BobR wrote:

void MyFunction( std::vector<std::string> const &Bstr ){
std::cout<<"in "<<__FUNCTION__<<" size="<<Bstr.size()
<<std::endl; //(1)

If you're going to be pedantic to the OP, then try using Standard C++
yourself. __FUNCTION__ is a g++-ism, and is not part of the Standard.

Yup, I done screwed up big-time. You are right. I am so very sorry. Can you
ever forgive me? Please?

Dang, you mean there are people out there who use something other than GCC?
<G>
[ "__FUNCTION__" and "__PRETTY_FUNCTION__" sure are handy. ]

Merry Christmas and a Happy New Year to all!

--
Bob R
POVrookie

[red floyd]

BobR wrote:

red floyd wrote in message ... Yup, I done screwed up big-time. You are right. I am so very sorry. Can you
ever forgive me? Please?

Dang, you mean there are people out there who use something other than GCC?
<G>
[ "__FUNCTION__" and "__PRETTY_FUNCTION__" sure are handy. ]

Merry Christmas and a Happy New Year to all!

[Entire post taken in the spirit it was intended]

No problem Bob. Happy Chanukah!

[Aris]

Hi all!
I want to make a function which will create file names as :
I will load with an integer
from 1 till 5 and receive a responce like this
"file1.txt","file2.txt"....."file5.txt"
But instead I get crazy things like theese:
file1.txt
file1.txt2
file1.txt23
file1.txt233@
can you help me?

#include <iostream.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>

char * Create_File_Name(int counter_files)
{
char *ch1="file";
char *ch2=".txt";
char string[2];
itoa(counter_files,string,10);
char *ch3=strcat(ch1,string);
char *fname=strcat(ch3,".txt");
return fname;
}
int main()
{

char* fname;
for(int i=1; i<5; i++)
{
fname=Create_File_Name(i);
cout<<fname<<endl;
}
int p;
cin>>p;
return 0;
}

[Luke Meyers]

There's unfortunately a great deal going wrong here. Your program
invokes undefined behavior, because the buffers you pass to strcat do
not have sufficient size to hold the concatenated strings. If you're
going to use the old C libraries, you should at least read up on them
to avoid such mistakes:
http://www.cplusplus.com/ref/cstring/strcat.html

That said, it's a bad idea to be using all this legacy, C-style stuff
in any case. Unless you are under some absurd constraint to do so, you
should instead use the STL's string, and associated practices. Here is
an updated, working version of your code:

#include <iostream> // for std::cout
#include <string> // for std::string
#include <sstream> // for std::stringstream

std::string createFileName(int fileIndex) {
std::stringstream stream;
stream << "file" << fileIndex << ".txt";
stream.flush();
return stream.str();
}

int main(void) {
for(int i=1; i<=5; i++) {
std::cout << createFileName(i) << "\n";
}
return 0;
}

Luke