Why does "wc -c" appear to add an extra byte?

[CrazedNerd]

[email protected]:~/c$ echo hello | wc -c
6

I'm pretty sure the word "hello" has five characters, why does wc say that there are 6 bytes in hello?

 

[MattWinter]

The strings are probably null-terminated and the null character takes a byte.

 

[sphen]

[email protected]:~/c$ echo hello | wc -c
6

I'm pretty sure the word "hello" has five characters, why does wc say that there are 6 bytes in hello?

The echo command adds a trailing newline character. The trailing newline character is counted by the wc command in your example. For the echo command, you can omit the trailing newline character with the "-n" switch.

$ echo hello
hello
$ echo -n hello
hello$ # Observe: No newline before the prompt.
$ echo hello | wc -c
6
$ echo -n hello | wc -c
5
$

Hints:

• All of these are different ways to represent the newline character in Unix, Linux, and current Macs:
  • \n
  • "line feed"
  • CTRL-J
  • ASCII 10, Hex 0x0A
  • "LF"
• In Unix and Linux and any Mac made in the last 20 years, the newline character is a single character.
• -> In Windows, the newline is a sequence of two characters: "carriage return" and then "line feed".
• On very old Macs that run the ancient "classic" MacOS operating system, newline was a single "carriage return" character.

 

[CrazedNerd]

The echo command adds a trailing newline character. The trailing newline character is counted by the wc command in your example. For the echo command, you can omit the trailing newline character with the "-n" switch.

$ echo hello
hello
$ echo -n hello
hello$ # Observe: No newline before the prompt.
$ echo hello | wc -c
6
$ echo -n hello | wc -c
5
$

Hints:

• All of these are different ways to represent the newline character in Unix, Linux, and current Macs:
  • \n
  • "line feed"
  • CTRL-J
  • ASCII 10, Hex 0x0A
  • "LF"
• In Unix and Linux and any Mac made in the last 20 years, the newline character is a single character.
• -> In Windows, the newline is a sequence of two characters: "carriage return" and then "line feed".
• On very old Macs that run the ancient "classic" MacOS operating system, newline was a single "carriage return" character.

That is correct, because when you turn off the newline feature:

[email protected]:~/c$ echo -n hello | wc -c
5

The strings are probably null-terminated and the null character takes a byte.

Is the null character the same thing as a newline?

 

[MattWinter]

Is the null character the same thing as a newline?

No, it isn't, but it's the same idea. In C a null character is used to denote the end of a string.