problem using strlen

[ricky]

What is worng with my code.
I can reads all the lines all right but it doesn't return me the length
of lines.
It returns 0 for each line

#include <fstream>
#include <istream>
#include <iostream>
#include <ostream>
#include <string>

int main()
{
fstream in("example.txt");
static string line;
int len = line.length();
while(getline(in,line))
{
cout<< line <<'\n';
cout<<len<<endl;
}
return 0;
}

[Stefan Näwe]

ricky schrieb:

What is worng with my code.
I can reads all the lines all right but it doesn't return me the length
of lines.
It returns 0 for each line

#include <fstream>
#include <istream>
#include <iostream>
#include <ostream>
#include <string>

int main()
{
fstream in("example.txt");
static string line;
int len = line.length();

How often does this ^^^^^ get executed ?

while(getline(in,line))
{
cout<< line <<'\n';
cout<<len<<endl;
}
return 0;
}

/S
--
Stefan Naewe
naewe.s_AT_atlas_DOT_de

[Siam]

You're creating an empty string (line)....and setting its length to the
len variable. As you then put strings into your line, the len variable
is never recalculated...it remains at what it started at i.e. 0. In
other words, the len variable doesn't dynamically update itself every
time you're line changes...you need to explicitly recalculate the
string length each time...ie.

while(getline(in,line))
{
len = line.length();
cout<< line <<'\n';
cout<<len<<endl;
}

ricky wrote:

What is worng with my code.
I can reads all the lines all right but it doesn't return me the length
of lines.
It returns 0 for each line

#include <fstream>
#include <istream>
#include <iostream>
#include <ostream>
#include <string>

int main()
{
fstream in("example.txt");
static string line;
int len = line.length();
while(getline(in,line))
{
cout<< line <<'\n';
cout<<len<<endl;
}
return 0;
}

[Eric Pruneau]

"ricky" <ri*******@yahoo.co.ina écrit dans le message de news:
11**********************@i42g2000cwa.googlegroups. com...

What is worng with my code.
I can reads all the lines all right but it doesn't return me the length
of lines.
It returns 0 for each line

#include <fstream>
#include <istream>
#include <iostream>
#include <ostream>
#include <string>

int main()
{
fstream in("example.txt");
static string line;
int len = line.length();

this should gives you 0

while(getline(in,line))

extract a line from the text file.. ok

{
cout<< line <<'\n';

print the line

cout<<len<<endl;

print len which is still 0 because you get the lenght before getting the
string

}
return 0;

oupss forget to close the file....

}

[ricky]

Great!! that worked
thanks Siam...
Siam wrote:

You're creating an empty string (line)....and setting its length to the
len variable. As you then put strings into your line, the len variable
is never recalculated...it remains at what it started at i.e. 0. In
other words, the len variable doesn't dynamically update itself every
time you're line changes...you need to explicitly recalculate the
string length each time...ie.

while(getline(in,line))
{
len = line.length();
cout<< line <<'\n';
cout<<len<<endl;
}

ricky wrote:

What is worng with my code.
I can reads all the lines all right but it doesn't return me the length
of lines.
It returns 0 for each line

#include <fstream>
#include <istream>
#include <iostream>
#include <ostream>
#include <string>

int main()
{
fstream in("example.txt");
static string line;
int len = line.length();
while(getline(in,line))
{
cout<< line <<'\n';
cout<<len<<endl;
}
return 0;
}

[ricky]

Yeah it is working now.
thanks to all of u.
Eric Pruneau wrote:

"ricky" <ri*******@yahoo.co.ina écrit dans le message de news:
11**********************@i42g2000cwa.googlegroups. com...

What is worng with my code.
I can reads all the lines all right but it doesn't return me the length
of lines.
It returns 0 for each line

#include <fstream>
#include <istream>
#include <iostream>
#include <ostream>
#include <string>

int main()
{
fstream in("example.txt");
static string line;
int len = line.length();

this should gives you 0

while(getline(in,line))

extract a line from the text file.. ok

{
cout<< line <<'\n';

print the line

cout<<len<<endl;

print len which is still 0 because you get the lenght before getting the
string

}
return 0;

oupss forget to close the file....

}

[Default User]

Siam wrote:

You're creating an empty string (line)

Please see my .sig below.

Brian
--
Please don't top-post. Your replies belong following or interspersed
with properly trimmed quotes. See the majority of other posts in the
newsgroup, or the group FAQ list:
<http://www.parashift.com/c++-faq-lite/how-to-post.htm>

[Default User]

ricky wrote:

Great!! that worked

Please see my .sig below.

Brian
--
Please don't top-post. Your replies belong following or interspersed
with properly trimmed quotes. See the majority of other posts in the
newsgroup, or the group FAQ list:
<http://www.parashift.com/c++-faq-lite/how-to-post.htm>

[Marcus Kwok]

Eric Pruneau <ep******@infinition.comwrote:

>
"ricky" <ri*******@yahoo.co.ina ?crit dans le message de news:
11**********************@i42g2000cwa.googlegroups. com...

>What is worng with my code.
I can reads all the lines all right but it doesn't return me the length
of lines.
It returns 0 for each line

#include <fstream>
#include <istream>
#include <iostream>
#include <ostream>
#include <string>

int main()
{
fstream in("example.txt");

[code elided]

oupss forget to close the file....

>}

It is not necessary, since fstream's destructor will take care of that
when "in" goes out of scope. That is the point of RAII.

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