string->int

[grubbymaster]

hello

i'm extracting from a file numbers that are stored on each line.
this is the only way i know to extract each line at a time from a file
, using <fstream> <ostream> :

char buffer[32];

ifstream LZW(sz_path);

while(!LZW.eof())
{
memset(buffer, 0, sizeof(buffer));

LZW.getline(buffer, sizeof(buffer)-1);
}

// buffer holds for example : "123" and i want to convert it to int x =
123 so that i can work with it later , like for example my_array[123] =
......

can anybody provide help in this aspect.

thank you,
alex

[Allan M. Bruce]

"grubbymaster" <gr**********@gmail.com> wrote in message
news:11**********************@u72g2000cwu.googlegr oups.com...

hello

i'm extracting from a file numbers that are stored on each line.
this is the only way i know to extract each line at a time from a file
, using <fstream> <ostream> :

char buffer[32];

ifstream LZW(sz_path);

while(!LZW.eof())
{
memset(buffer, 0, sizeof(buffer));

LZW.getline(buffer, sizeof(buffer)-1);
}

// buffer holds for example : "123" and i want to convert it to int x =
123 so that i can work with it later , like for example my_array[123] =
.....

can anybody provide help in this aspect.

thank you,
alex

have a look at sscanf()
Allan

[spibou]

grubbymaster wrote:

hello

i'm extracting from a file numbers that are stored on each line.
this is the only way i know to extract each line at a time from a file
, using <fstream> <ostream> :
fstream and ostream are not C.
// buffer holds for example : "123" and i want to convert it to int x =
123 so that i can work with it later , like for example my_array[123] =

If I understand correctly what you want , atoi() is what you're looking
for.

[spibou]

I posted the above message on comp.lang.c ; I have no idea
how it ended up here as well.

Spiros Bousbouras

[santosh]

sp****@gmail.com wrote:

grubbymaster wrote:

.... snip ...

// buffer holds for example : "123" and i want to convert it to int x =
123 so that i can work with it later , like for example my_array[123] =

If I understand correctly what you want , atoi() is what you're looking for.

A better way is to use sscanf() or strtol(). atoi() does not indicate
failure.

[wittempj]

grubbymaster wrote:

hello

i'm extracting from a file numbers that are stored on each line.
this is the only way i know to extract each line at a time from a file
, using <fstream> <ostream> :

char buffer[32];

ifstream LZW(sz_path);

while(!LZW.eof())
{
memset(buffer, 0, sizeof(buffer));

LZW.getline(buffer, sizeof(buffer)-1);
}

// buffer holds for example : "123" and i want to convert it to int x =
123 so that i can work with it later , like for example my_array[123] =
.....

can anybody provide help in this aspect.

thank you,
alex

The faq gives a direction on how to approach this, see
http://www.parashift.com/c++-faq-lit....html#faq-39.2

[grubbymaster]

sp****@gmail.com a scris:

grubbymaster wrote:

hello

i'm extracting from a file numbers that are stored on each line.
this is the only way i know to extract each line at a time from a file
, using <fstream> <ostream> :

fstream and ostream are not C.

// buffer holds for example : "123" and i want to convert it to int x =
123 so that i can work with it later , like for example my_array[123] =

If I understand correctly what you want , atoi() is what you're looking
for.

10x alot. can believe it was that simple.i've searched google before
posting and couldn't find what i was looking for.

bye

[Marcus Kwok]

In comp.lang.c++ sp****@gmail.com wrote:

grubbymaster wrote:

hello

i'm extracting from a file numbers that are stored on each line.
this is the only way i know to extract each line at a time from a file
, using <fstream> <ostream> :

fstream and ostream are not C.

But they are C++. The OP crossposted to both clc and clc++, which is
usually not a good idea, since they are different languages.

// buffer holds for example : "123" and i want to convert it to int x =
123 so that i can work with it later , like for example my_array[123] =

If I understand correctly what you want , atoi() is what you're looking
for.

I would recommend strtod(), because if you use atoi() you have no way of
knowing whether the conversion was successful.

Personally I would use stringstreams, but those are not C so I will
refrain from posting that solution in this message.

--
Marcus Kwok
Replace 'invalid' with 'net' to reply

[red floyd]

grubbymaster wrote:

hello

i'm extracting from a file numbers that are stored on each line.
this is the only way i know to extract each line at a time from a file
, using <fstream> <ostream> :

char buffer[32];

ifstream LZW(sz_path);

while(!LZW.eof())
{
memset(buffer, 0, sizeof(buffer));

LZW.getline(buffer, sizeof(buffer)-1);
}

// buffer holds for example : "123" and i want to convert it to int x =
123 so that i can work with it later , like for example my_array[123] =
.....

comp.lang.c removed from headers.

Other people have addressed the conversion issue (speaking personally,
I'd use a stringstream). So I'll address the two other problems.

Your read loop is incorrect, you will get an extra read upon EOF.
Search the FAQ. The idiom you want is:

while (LZW.getline(...))
{
}

In addition, you should probably use a std::string instead of a char
array.

e.g.

#include <string>
#include <fstream>

// ... redacted

std::string buffer;
ifstream LZW(sz_path);

while (std::getline(LZW, buffer))
{
// do something with buffer.
}

[Uwe Thormann]

hello,

#include<fstream>
#include<sstream>
#include<string>
#include<iostream>

int main(){
int a;
std::ifstream LZW("123.txt");
std::string buffer;

while(LZW >> buffer){
std::stringstream streambuffer(buffer);
streambuffer >> a;
std::cout << 2*a << std::endl; // for example
}
}

Uwe

[Keith Thompson]

Uwe Thormann <uw*********@gmx.de> writes:

hello,

#include<fstream>
#include<sstream>
#include<string>
#include<iostream>

int main(){
int a;
std::ifstream LZW("123.txt");
std::string buffer;

while(LZW >> buffer){
std::stringstream streambuffer(buffer);
streambuffer >> a;
std::cout << 2*a << std::endl; // for example
}
}

First, without context, it's hard to tell what you're talking about.
I know that groups.google.com has problems with this, and the
workaround has been posted in comp.lang.c hundreds of times, but
you're not posting through Google, so I don't know what to tell you.

Second, you posted a C++ program and directed followups to
comp.lang.c. Was that a typo? I've directed followups to
comp.lang.c++.

--
Keith Thompson (The_Other_Keith) ks***@mib.org <http://www.ghoti.net/~kst>
San Diego Supercomputer Center <*> <http://users.sdsc.edu/~kst>
We must do something. This is something. Therefore, we must do this.

[Rolf Magnus]

Keith Thompson wrote:

Uwe Thormann <uw*********@gmx.de> writes:

hello,

#include<fstream>
#include<sstream>
#include<string>
#include<iostream>

int main(){
int a;
std::ifstream LZW("123.txt");
std::string buffer;

while(LZW >> buffer){
std::stringstream streambuffer(buffer);
streambuffer >> a;
std::cout << 2*a << std::endl; // for example
}
}
First, without context, it's hard to tell what you're talking about.
I know that groups.google.com has problems with this, and the
workaround has been posted in comp.lang.c hundreds of times, but
you're not posting through Google, so I don't know what to tell you.

Me neither. knode quotes the original posting by default when replying. Uwe
must have switched that off explicitly somehow or cut the quoting away for
some reason.
Second, you posted a C++ program and directed followups to
comp.lang.c. Was that a typo? I've directed followups to
comp.lang.c++.

That was probably due to knode. When replying to a cross-posting, it adds a
follow-up to the first group in the list. It's easy to overlook that.

[ais523]

Keith Thompson wrote:

<snip>

First, without context, it's hard to tell what you're talking about.
I know that groups.google.com has problems with this, and the
workaround has been posted in comp.lang.c hundreds of times, but
you're not posting through Google, so I don't know what to tell you.

<snip>

In fact, the Google interface has now been fixed in this regard. This
message was written via the 'Reply' link at the bottom of your message,
and the quoting was done automatically; I even had a chance to snip it.