strlen() counts characters even after the null terminator

Question

#include<stdio.h>
#include<string.h>

int main() {
char a[100]="1234\0567"; //Answer: 6
int len=strlen(a);
printf("%d",len); 
}

This code prints 6 as the answer. Shouldn't it print 4 since strlen returns the count until the null character is encountered?

However when a space is included between \0 and 5. It returns 4 as the answer

char a[100]="1234\0 567"; //Answer: 4

Am I missing something?

Answer 1

You first version has the octal number \056 not the \0 character

Edit: in the similar situations use \000 octal sequence instead:

/* from your example*/ char a[100]="1234\000567";

Answer 2

The \056 is a single character, with the octal ASCII code (56)₈, decimal - (46)₁₀.