escapping \n, \t etc.

[Prasad]

Hi All,

when you assign a string having \n, \t or \r etc.
like for eg str = "Hello\nWorld" ;

And do printf (str)

it will be printed as
Hello
World.

But, how can I print it as "Hello\nWorld"?

What is the best we to do it?

Thanks and regards,
Prasad.

[Christopher Benson-Manica]

Prasad <pr************@gmail.comwrote:

when you assign a string having \n, \t or \r etc.
like for eg str = "Hello\nWorld" ;

But, how can I print it as "Hello\nWorld"?

Escape the backslash:

const char *str = "Hello\\nWorld";

printf()'s documentation is your friend.

--
C. Benson Manica | I *should* know what I'm talking about - if I
cbmanica(at)gmail.com | don't, I need to know. Flames welcome.

[Keith Thompson]

Christopher Benson-Manica <at***@ukato.freeshell.orgwrites:

Prasad <pr************@gmail.comwrote:

>when you assign a string having \n, \t or \r etc.
like for eg str = "Hello\nWorld" ;

>But, how can I print it as "Hello\nWorld"?

Escape the backslash:

const char *str = "Hello\\nWorld";

printf()'s documentation is your friend.

printf()'s documentation won't help here. The fact that "\n" contains
a newline character, while "\\n" contains a backslash followed by 'n',
is determined by the syntax of string literals.

Incidentally, it wasn't clear to me whether the OP wanted to do this
conversion in his source, or at run time. For example, it could be
useful to have a function, that, given the string "Hello\nWorld",
would print

Hello\nWorld

rather than

Hello
World

This requires scanning the string and replacing each newline character
with the two-character sequence of a backslash and an 'n'. There's no
function in the standard library that will automatically do this for
you, but it's easy enough to write the code yourself.

--
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.

[CBFalconer]

Prasad wrote:

>
when you assign a string having \n, \t or \r etc.
like for eg str = "Hello\nWorld" ;

And do printf (str)

it will be printed as
Hello
World.

But, how can I print it as "Hello\nWorld"?

What is the best we to do it?

printf("Hello\\nWorld\n");
or
printf("%s\n", "Hello\\nWorld");
or
puts("Hellow\\nWorld");
or
printf("%s%c%s\n", "Hello", '\\', "nWorld");
or
think up some other possibilities.

--
"The most amazing achievement of the computer software industry
is its continuing cancellation of the steady and staggering
gains made by the computer hardware industry..." - Petroski

[Joe Wright]

Prasad wrote:

Hi All,

when you assign a string having \n, \t or \r etc.
like for eg str = "Hello\nWorld" ;

And do printf (str)

it will be printed as
Hello
World.

But, how can I print it as "Hello\nWorld"?

What is the best we to do it?

Thanks and regards,
Prasad.

#include <stdio.h>
int main(void)
{
char str[] = "Hello\nWorld.";
char *s = str;
int c;
puts(str);
putchar('"');
while ((c = *s++) != 0)
if (c == '\n') {
putchar('\\');
putchar('n');
} else {
putchar(c);
}
putchar('"');
return 0;
}
--
Joe Wright
"Everything should be made as simple as possible, but not simpler."
--- Albert Einstein ---

[santosh]

Joe Wright wrote:

Prasad wrote:

Hi All,

when you assign a string having \n, \t or \r etc.
like for eg str = "Hello\nWorld" ;

And do printf (str)

it will be printed as
Hello
World.

But, how can I print it as "Hello\nWorld"?

What is the best we to do it?

Thanks and regards,
Prasad.

#include <stdio.h>
int main(void)
{
char str[] = "Hello\nWorld.";
char *s = str;
int c;
puts(str);
putchar('"');
while ((c = *s++) != 0)
if (c == '\n') {
putchar('\\');

Why do you need two backslashes here? Won't one do?

putchar('n');
} else {
putchar(c);
}
putchar('"');
return 0;
}

[Richard Heathfield]

santosh said:

Joe Wright wrote:

<snip>

> putchar('\\');

Why do you need two backslashes here? Won't one do?

No.

See K&R2, page 8, or, if you prefer, 3.1.3.4 Character constants:

simple-escape-sequence: one of
\' \" \? \\
\a \b \f \n \r \t \v

'\' would be a single quote and an escaped-single-quote. This would mean
that the opening single quote was not matched. It is analogous to "\"
(which is an unterminated string).

--
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999
http://www.cpax.org.uk
email: rjh at the above domain, - www.

[Christopher Benson-Manica]

Keith Thompson <ks***@mib.orgwrote:

printf()'s documentation won't help here. The fact that "\n" contains
a newline character, while "\\n" contains a backslash followed by 'n',
is determined by the syntax of string literals.

I suppose that's most correct, but man printf on my system does indeed
discuss the various character escape sequences, hence my comment.

--
C. Benson Manica | I *should* know what I'm talking about - if I
cbmanica(at)gmail.com | don't, I need to know. Flames welcome.