Use pointer-pointer to find string length

Use pointer-pointer to find string length:
The result of pointer-pointer is the number of elements between two pointers, but it should be noted that the two pointers to be subtracted must belong to the same space.

#include<stdio.h>

int my_strlen(char* str)
{
    
    
	char* start=str;
	char* end=str;
	while(*end!='\0')
	{
    
    
		end++;
	}
	return end-start;
}
int main()
{
    
    
	char arr[]="welcome to China";
	int len=my_strlen(arr);
	printf("%d\n",len);
}

The results are as follows:

Caicai's code, I hope it can help you!