Size of string literal consisting of escaped characters

Question

Code in question:

#include <iostream>
#include <cstring>
using namespace std;

int main()
{
    cout << sizeof("\n\r\t") << endl; // prints 4
    cout << strlen("\n\r\t") << endl; // print 3
    return 0;
}

I am confused because I always thought that it is standard that sizeof char is always 1 byte, but in the above code, it is printing 4.

Is there an explanation for this or is there an exception to this rule for escaped characters? Please enlighten me

Answer 1

The only difference here is that strlen does not include the null terminating character while sizeof will. The C documentation for strlen is actually better in this case since it includes the statement:

The null character is excluded from the length.

For some clarification a string literal is an array which includes a null terminating character, from the the draft C++ standard section 2.14.5 String literals paragraph 8 says:

Ordinary string literals and UTF-8 string literals are also referred to as narrow string literals. A narrow string literal has type “array of n const char”, where n is the size of the string as defined below, and has static storage duration (3.7).

and paragraph 15 says:

[...]The size of a narrow string literal is the total number of escape sequences and other characters, plus at least one for the multibyte encoding of each universal-character-name, plus one for the terminating ’\0’.

and sizeof applied to an array will give you the total number of bytes in the array from section 5.3.3 Sizeof paragraph 3:

[...]When applied to an array, the result is the total number of bytes in the array. This implies that the size of an array of n elements is n times the size of an element.