The printf()
documentation says that if someone wants to print %
in C, he can use:
printf("%%")
Why is it not:
printf("\%")
as with other special characters?
The printf()
documentation says that if someone wants to print %
in C, he can use:
printf("%%")
Why is it not:
printf("\%")
as with other special characters?
The backslash is processed by the compiler when interpreting the source text of the program. So the common result is that the source text
"\%"
produces a string containing ”%”.The format string is interpreted by the
printf
routine, so it processes the characters passed to it. By this time, the backslash is no longer present, soprintf
never sees it.Technically,
\%
is not legal in a string literal. The character\
starts an escape sequence, and the only legal escape sequences are listed in C 2011 6.4.4.4 1. They are\
followed by'
,"
,?
,\
,a
,b
,f
,n
,r
,t
,v
, one to three octal digits,x
and hexadecimal digits,u
and four hexadecimal digits, orU
and eight hexadecimal digits.If
printf
had been designed so that a backslash would escape a percent, then you would have to pass it a backslash by escaping the backslash in the source text, so you would have to write:Because the
%
is handled byprintf
. It is not a special character in C, butprintf
itself treats it differently.The convention is that special characters escape themselves. So, rather than using backslash to escape the percent, it escapes itself. (Note that to pass a backslash to
printf
, you'd have to write the string literal as"\\%"
.)You can do it !!!!!
The problem exist with printf and differ from the compiler you use .. With wxWidget lib you can not use printf with two escape sequences
don t go. But if you use
you are right. A plus