read system-call

[=?ISO-8859-1?Q?Andreas_M=FCller?=]

Hi,

I'm working on a Linux-programm with a signal-handler and therfore I
need to use the read-system-call instead of cin.get or sth. like that.
With getline my program works fine, it reads a line from stdin and
passes it to a buffer but when I try to replace getline with read, sth.
is wrong!? can u help me?

//this works fine
length=cin.getline(cmd_buffer1,512).gcount();
for (z=0;z<length;++z){
cmd_buffer[z]=cmd_buffer1[z];
cmd_buffer[length]='\0';

//using read instead if cin.getline !?
length=read(STDIN_FILENO, cmd_buffer1, 80);


the reason why I use the for-loop (which I won't need when using
getline) is that I think I have to set the termination char (\0) myself
(when using read), is that correct?

 

[John Harrison]

Hi,

I'm working on a Linux-programm with a signal-handler and therfore I
need to use the read-system-call instead of cin.get or sth. like that.
With getline my program works fine, it reads a line from stdin and
passes it to a buffer but when I try to replace getline with read, sth.
is wrong!? can u help me?

//this works fine
length=cin.getline(cmd_buffer1,512).gcount();
for (z=0;z<length;++z){
cmd_buffer[z]=cmd_buffer1[z];
cmd_buffer[length]='\0';

//using read instead if cin.getline !?
length=read(STDIN_FILENO, cmd_buffer1, 80);


the reason why I use the for-loop (which I won't need when using
getline) is that I think I have to set the termination char (\0) myself
(when using read), is that correct?

Getline stops reading when it gets to the end of a line, read just reads
how many bytes you tell it to read. So in your example read will always
read 80 bytes, no matter where the end of the line is.

john

 

[=?ISO-8859-1?Q?Andreas_M=FCller?=]

Hi,

I'm working on a Linux-programm with a signal-handler and therfore I
need to use the read-system-call instead of cin.get or sth. like that.
With getline my program works fine, it reads a line from stdin and
passes it to a buffer but when I try to replace getline with read, sth.
is wrong!? can u help me?

//this works fine
length=cin.getline(cmd_buffer1,512).gcount();
for (z=0;z<length;++z){
cmd_buffer[z]=cmd_buffer1[z];
cmd_buffer[length]='\0';

//using read instead if cin.getline !?
length=read(STDIN_FILENO, cmd_buffer1, 80);


the reason why I use the for-loop (which I won't need when using
getline) is that I think I have to set the termination char (\0) myself
(when using read), is that correct?

Getline stops reading when it gets to the end of a line, read just reads
how many bytes you tell it to read. So in your example read will always
read 80 bytes, no matter where the end of the line is.

ya, this is why I copy all the chars in a separate array.

 

[Huihong]

You can find lots of sample code to check how people use read as a
funtion call

http://www.codase.com/search/call?name=read

 

[Maxim Yegorushkin]

Hi,

I'm working on a Linux-programm with a signal-handler and therfore I
need to use the read-system-call instead of cin.get or sth. like that.
With getline my program works fine, it reads a line from stdin and
passes it to a buffer but when I try to replace getline with read, sth.
is wrong!? can u help me?

//this works fine
length=cin.getline(cmd_buffer1,512).gcount();
for (z=0;z<length;++z){
cmd_buffer[z]=cmd_buffer1[z];
cmd_buffer[length]='\0';

//using read instead if cin.getline !?
length=read(STDIN_FILENO, cmd_buffer1, 80);

You can easily wrap a file descriptor with iostream interface, just
like I did it for FILE*. http://rsdn.ru/Forum/?mid=942482