字符串与数组

#define _CRT_SECURE_NO_WARNINGS
#include<stdlib.h>
#include<string.h>
#include<stdio.h>

void main()
{
	char a[] = "i am a student";  //默认 结尾，为字符串（字符数组表示）
	char b[64];

	printf("strlen(a)=%d,sizeof(a)=%d
", strlen(a), sizeof(a));   //str为字符串长度14  sizeof为数组长度15，包括
	int i = 0;
	for (i = 0; *(a + i) != ''; i++)  //  a[i] = *(a+i)  a代表数组首地址，i步长为1
	{
		*(b + i) = *(a + i);
	}
	*(b + i) = '';    //若不将最后一位设置为,则表示单纯的字符数组，不是字符串，不能用%s输出
	printf("a:%s
", a);
	printf("b:%s
", b);
	system("pause");
	return ;
}

void copystr(char * from,char * to)      //拷贝字符串函数
{
	int i;
	//1.
	//for (i = 0; *(from + i) != ''; i++)
	//{
	//	//to[i] = from[i];            //to[i] 和 *(to+i)一样
	//	*(to + i) = *(from + i);
	//}
	//*(to + i) = '';

	//2.
	//for (; *from != '';)
	//{
	//	*to++ = *from++;  //*to=*from         to++;from++
	//}
	//*to = '';

	//3
	//while ((*to = *from) != '')
	//{
	//	to++;
	//	from++;
	//}

	
	while ((*to++ = *from++) != '')
	{

	}

	return;
}
void main()

{
	char from[] = "i am a student";  //提前给from 和 to 分配内存
	char to[64];
	copystr(from, to);
	printf("%s
",to);
	system("pause");
	return;
}