c - *s 等于 s[i] 吗？

Question

关闭。此题需要 details or clarity 。目前不接受答案。

---

想要改进这个问题吗？通过 editing this post 添加详细信息并澄清问题.

已关闭 6 年前。

Improve this question

K&R C 第 106 页，strcmp函数，它需要指针 *s和*t作为参数，但在 for 中循环，它指定

s[i]==t[i]     

作为条件。

只是想确认一下，对于数组，如

*(s+i) and s[i] 

是同义的，因此函数语句可以使用 s[i]而不是*s ？

Answer 1

来自 C 标准(6.5.2.1 数组下标)

2 A postfix expression followed by an expression in square brackets [] is a subscripted designation of an element of an array object. The definition of the subscript operator [] is that E1[E2] is identical to (*((E1)+(E2))). Because of the conversion rules that apply to the binary + operator, if E1 is an array object (equivalently, a pointer to the initial element of an array object) and E2 is an integer, E1[E2] designates the E2-th element of E1 (counting from zero).

因此

a[i] 等价于 *( a + i ) 又等价于 i[a]

例如

int a[1] = { 10 };

printf( "a[0] == *( a + 0 ) is %s\n", a[0] == *( a + 0 ) ? "true" : "false" );
printf( "a[0] == 0[a] is %s\n", a[0] == 0[a] ? "true" : "false" );