在C中如何在字符串中找到'\\'字符？

Question

Suppose I have a string entered by the user asdfgh\\hj , and I wish to find out the index of \\ character in a String. How I can do it in C?

I tried strchr() function as strchr("asdfgh\\hj",'\\') but compiler throws an error.

Then I used == operator but same problem with it — again the compiler throws an error.

Answer 1

I tried strchr() function as strchr("asdfgh\\hj",'\\') but compiler throws an error

That's the right function! The reason you get an error is because \\ is a special "escape" character. It is used to define "special" non-printable characters, such as newline \\n . That is why the backslash itself \\ needs escaping, like this:

strchr("asdfgh\\hj",'\\')

Answer 2

尝试这个：

strchr("asdfgh\\hj",'\\')

Answer 3

C standard says, C11 6.4.4.4:

The double-quote " and question-mark ? are representable either by themselves or by the escape sequences \\" and \\? , respectively, but the single-quote ' and the backslash \\ shall be represented, respectively, by the escape sequences \\' and \\\\ .

So use

strchr("asdfgh\\hj",'\\')  

instead.

Answer 4

In C the backslash is used for hard typed characters like \\n . So you need to write \\\\ for the \\ itself:

char *backslash = strch("some text containing \\ ...", '\\');

Note that in the string you provided the \\ also need to be writen \\\\ otherwise it will be considered as \\h which has no meaning.