Hey all, I have a c function im putting into c++ (dont ask why, tell
you the truth, I really dont know!). I am having a bit of problem
deciding on how to use a new method of fread.
Here is the (working) C code:
float read_p(FILE *file, int datatype)
{
float res;
unsigned char u, b1, b2;
switch(datatype )
{
case 1:
fread(&u, sizeof(unsigned char), 1, file);
res = u;
break;
case 4:
fread(&res, sizeof(float), 1, file);
break;
default:
printf ("\n Error \n\n");
res = 0.0;
exit(1);
}
return res;
}
Here is what I have so far.. (I had to re-do some of the file IO).
float read_p(ifstream &file1, int datatype)
{
float res;
unsigned char u, b1, b2;
switch(datatype )
{
case 1:
fread(&u, sizeof(unsigned char), 1, &file1);
res = u;
break;
case 4:
fread(&res, sizeof(float), 1, &file1);
break;
default:
cout<<"Error"<< endl;
res = 0.0;
exit(1);
}
return res;
}
Anyone have a comment on how I could use something like fread? Sorry I
am not very good at c++! Havnt used it in years.
6  4348  ry******@gmail. com wrote:
Hey all, I have a c function im putting into c++ (dont ask why, tell
you the truth, I really dont know!). I am having a bit of problem
deciding on how to use a new method of fread.
Huh? "A new method of fread"? You can't use 'fread' with C++ I/O
streams. They have their own 'read' member function for that.
[..]
Get yourself a decent book. The sooner, the better.
V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask
On Aug 28, 2:59 pm, "Victor Bazarov" <v.Abaza...@com Acast.netwrote:
ryans...@gmail. com wrote:
Hey all, I have a c function im putting into c++ (dont ask why, tell
you the truth, I really dont know!). I am having a bit of problem
deciding on how to use a new method of fread.
Huh? "A new method of fread"? You can't use 'fread' with C++ I/O
streams. They have their own 'read' member function for that.
[..]
Get yourself a decent book. The sooner, the better.
V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask
Just phrased that poorly. What function would be good to use to read
the stuff in instead of fread? read?
I dont want to buy a book for a couple of lines of code. ry******@gmail. com wrote:
Hey all, I have a c function im putting into c++ (dont ask why, tell
you the truth, I really dont know!). I am having a bit of problem
deciding on how to use a new method of fread.
Here is the (working) C code:
.... snipped
Here is what I have so far.. (I had to re-do some of the file IO).
float read_p(ifstream &file1, int datatype)
^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^
If anything, this should be:
float read_p(istream &file1, int datatype)
Use and istream reference instead of an ifstream reference so you can
use any istream based type.
{
float res;
unsigned char u, b1, b2;
switch(datatype )
{
case 1:
fread(&u, sizeof(unsigned char), 1, &file1);
what do you do about errors ?
res = u;
break;
case 4:
fread(&res, sizeof(float), 1, &file1);
what do you do when there are not enough bytes in the file ?
You could use :
file1.read( reinterpret_cas t<char *>( & res ), sizeof( res ) );
break;
default:
cout<<"Error"<< endl;
res = 0.0;
exit(1);
}
return res;
}
Anyone have a comment on how I could use something like fread? Sorry I
am not very good at c++! Havnt used it in years.
Use it more often.
On 2007-08-28 22:49, ry******@gmail. com wrote:
Hey all, I have a c function im putting into c++ (dont ask why, tell
you the truth, I really dont know!). I am having a bit of problem
deciding on how to use a new method of fread.
Here is the (working) C code:
float read_p(FILE *file, int datatype)
{
float res;
unsigned char u, b1, b2;
switch(datatype )
{
case 1:
fread(&u, sizeof(unsigned char), 1, file);
res = u;
break;
case 4:
fread(&res, sizeof(float), 1, file);
break;
default:
printf ("\n Error \n\n");
res = 0.0;
exit(1);
}
return res;
}
Here is what I have so far.. (I had to re-do some of the file IO).
float read_p(ifstream &file1, int datatype)
{
float res;
unsigned char u, b1, b2;
switch(datatype )
{
case 1:
fread(&u, sizeof(unsigned char), 1, &file1);
res = u;
break;
case 4:
fread(&res, sizeof(float), 1, &file1);
break;
default:
cout<<"Error"<< endl;
res = 0.0;
exit(1);
}
return res;
}
float read_p(std::ist ream& file, int datatype)
{
switch (datatype)
{
case 1:
unsigned char c;
file >c;
return c;
case 4;
float f;
file >f;
return f;
default:
// ...
}
And add extensive error checking.
--
Erik Wikström
On 2007-08-28 17:14:58 -0400, Erik Wikström <Er***********@ telia.comsaid:
On 2007-08-28 22:49, ry******@gmail. com wrote:
>Hey all, I have a c function im putting into c++ (dont ask why, tell
you the truth, I really dont know!). I am having a bit of problem
deciding on how to use a new method of fread.
Here is the (working) C code:
float read_p(FILE *file, int datatype)
{
float res;
unsigned char u, b1, b2;
switch(datatype )
{
case 1:
fread(&u, sizeof(unsigned char), 1, file);
res = u;
break;
case 4:
fread(&res, sizeof(float), 1, file);
break;
default:
printf ("\n Error \n\n");
res = 0.0;
exit(1);
}
return res;
}
Here is what I have so far.. (I had to re-do some of the file IO).
float read_p(ifstream &file1, int datatype)
{
float res;
unsigned char u, b1, b2;
switch(datatype )
{
case 1:
fread(&u, sizeof(unsigned char), 1, &file1);
res = u;
break;
case 4:
fread(&res, sizeof(float), 1, &file1);
break;
default:
cout<<"Error"<< endl;
res = 0.0;
exit(1);
}
return res;
}
float read_p(std::ist ream& file, int datatype)
{
switch (datatype)
{
case 1:
unsigned char c;
file >c;
return c;
case 4;
float f;
file >f;
return f;
default:
// ...
}
This won't work. Presumably, the file contains binary data, which is
why the original code uses fread. The stream extractors read formatted
text, which is an entirely different animal.
--
Pete
Roundhouse Consulting, Ltd. ( www.versatilecoding.com) Author of "The
Standard C++ Library Extensions: a Tutorial and Reference
( www.petebecker.com/tr1book)
On 2007-08-29 01:30, Pete Becker wrote:
On 2007-08-28 17:14:58 -0400, Erik Wikström <Er***********@ telia.comsaid:
>On 2007-08-28 22:49, ry******@gmail. com wrote:
>>Hey all, I have a c function im putting into c++ (dont ask why, tell
you the truth, I really dont know!). I am having a bit of problem
deciding on how to use a new method of fread.
Here is the (working) C code:
float read_p(FILE *file, int datatype)
{
float res;
unsigned char u, b1, b2;
switch(datatype )
{
case 1:
fread(&u, sizeof(unsigned char), 1, file);
res = u;
break;
case 4:
fread(&res, sizeof(float), 1, file);
break;
default:
printf ("\n Error \n\n");
res = 0.0;
exit(1);
}
return res;
}
Here is what I have so far.. (I had to re-do some of the file IO).
float read_p(ifstream &file1, int datatype)
{
float res;
unsigned char u, b1, b2;
switch(datatype )
{
case 1:
fread(&u, sizeof(unsigned char), 1, &file1);
res = u;
break;
case 4:
fread(&res, sizeof(float), 1, &file1);
break;
default:
cout<<"Error"<< endl;
res = 0.0;
exit(1);
}
return res;
}
float read_p(std::ist ream& file, int datatype)
{
switch (datatype)
{
case 1:
unsigned char c;
file >c;
return c;
case 4;
float f;
file >f;
return f;
default:
// ...
}
This won't work. Presumably, the file contains binary data, which is
why the original code uses fread. The stream extractors read formatted
text, which is an entirely different animal.
Ah, I knew there was a reason it seemed so simple, my apologies.
--
Erik Wikström This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
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