-s 在这段代码中的作用是什么，其中 s 是一个 char 指针？

Question

In this code

strcpy(s, "bacalaureat");
i = strchr(s, 'a') - s; // i = 1

The value of i is 1. Why is that, and what's the role of the -s above?

Answer 1

From the reference :

char *strchr( const char *str, int ch );

Finds the first occurrence of ch ... in the null-terminated byte string pointed to by str

So strchr(s, 'a') will return a pointer to the first occurrence of the character a , which is the second character in s .

Subtracting s from this result is just pointer arithmetic which gives you the index of the character a in s , which is 1.