# Extra Clang Tools 21.1.6 documentation

## clang-tidy - bugprone-string-literal-with-embedded-nul

# bugprone-string-literal-with-embedded-nul

Finds occurrences of string literal with embedded NUL character and validates their usage.

## Invalid escaping

Special characters can be escaped within a string literal by using their hexadecimal encoding like `\x42`. A common mistake is to escape them like this `\0x42` where the `\0` stands for the NUL character.

    const char* Example[] = "Invalid character: \0x12 should be \x12";
    const char* Bytes[] = "\x03\0x02\0x01\0x00\0xFF\0xFF\0xFF";

## Truncated literal

String-like classes can manipulate strings with embedded NUL as they are keeping track of the bytes and the length. This is not the case for a `char*` (NUL-terminated) string.

A common mistake is to pass a string-literal with embedded NUL to a string constructor expecting a NUL-terminated string. The bytes after the first NUL character are truncated.

    std::string str("abc\0def");  // "def" is truncated
    str += "\0";                  // This statement is doing nothing
    if (str == "\0abc") return;   // This expression is always true