问题描述
这是查找特定字母出现的简单功能.
This is a simple function for finding occurrences of a specific letter.
1: int count_x(char *p, char a)
2: {
3: int count = 0;
4: while(*p != '\0')
5: {
6: if (*p == a)
7: count++;
8: p++;
9: }
10: return count;
11: }
我们可以使用p[n]来访问特定元素，或者我们可以取消引用*p并获取该数组的第一个元素作为示例，而我们通常会做所有这些事情.
对我来说奇怪的是位于第8行.当我们写p++时，我们从一开始就获得了传递-1符号的数组.因此，如果它是hello, world，那么它将是ello, world.我们正在某种程度上遍历索引，但是我真的不明白如何做.
We can get access to a specific element by using p[n], or we can dereference it *p and get a first element of that array as an example, and all of that stuff we usually do.
The strange thing to me is located at the line number 8.When we write p++, we are getting the array we passed -1 symbol from the beginning. So if it was hello, world then it would be ello, world.We are somehow iterating throuhg the indices but i don't really understand how.
我可以解释所有这些东西如何工作吗?
Can i have an explanation of how all of that stuff works?
推荐答案
循环条件*p != '\0'表示:*迭代直到p指向的值是'\0'.循环体内的语句
The loop condition *p != '\0' means: *iterate until the value pointed by p is '\0'. The statement inside the loop body
p++;
递增指向所传递字符串的下一个字符的指针.
increments the pointer to next character of the string passed.
第一次迭代
+--------+--------+--------+--------+--------+--------+--------+--- ----+--------+--------+--------+--------+
| | | | | | | | | | | | |
| 'h' | 'e' | 'l' | 'l' | 'o' | ',' | 'w' | 'o' | 'r' | 'l' | 'd' | '\0' |
| | | | | | | | | | | | |
+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+
^
|
p
第二次迭代:
+--------+--------+--------+--------+--------+--------+--------+--- ----+--------+--------+--------+--------+
| | | | | | | | | | | | |
| 'h' | 'e' | 'l' | 'l' | 'o' | ',' | 'w' | 'o' | 'r' | 'l' | 'd' | '\0' |
| | | | | | | | | | | | |
+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+--------+
^
|
p
，依此类推.当p到达点'\0'时，条件*p != '\0'变为false，循环终止.在每次迭代中，指针p都会更改其指向的位置.字符串保留在其初始存储位置.
and so on. When p comes to point '\0', condition *p != '\0' becomes false and loop terminates.On every iteration it is the pointer p which changes the location where it points. String remain at its initial stored location.
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