C语言大厂面试技巧及strcpy()函数示例详解

#include<stdio.h>
void my_strcpy(char* dest, char* src)
{
	while (*src!='\0')
	{
		*dest = *src;
		dest++;
		src++;
	}
	*dest = *src;//处理字符串的结束标志'\0'
	//*dest = '\0';这样处理并非是不行，但是会给阅读代码的造成一种错觉\
	即这个'\0'是自己放进去的，而不是从源字符串拷贝进去的
}
int main()
{
	char arr1[20] = { 0 };
	char arr2[] = "hello";
 
   my_strcpy(arr1, arr2);
	printf("%s\n", arr1);
	return 0;
}

#include<stdio.h>
#include<assert.h>
void my_strcpy(char* dest, char* src)
{
	assert(dest != NULL);
	assert(src != NULL);
   //当然，此处也可以将两个合并成一个：assert( dest && src )
	while (*src!='\0')
	{
		*dest = *src;
		dest++;
		src++;
	}
	*dest = *src;
}
int main()
{
	char arr1[20] = { 0 };
	char arr2[] = "hello";
 
   my_strcpy(arr1, arr2);
	printf("%s\n", arr1);
	return 0;
}

#include<stdio.h>
#include<assert.h>
void my_strcpy(char* dest, char* src)
{
	assert( dest && src );
	while(*dest++ = *src++)//'\0'的ascii码值为0，为假，会退出循环
	{
		;
	}
}
int main()
{
	char arr1[20] = { 0 };
	char arr2[] = "hello";
   my_strcpy(arr1, arr2);
	printf("%s\n", arr1);
	return 0;
}

#include<stdio.h>
#include<assert.h>
char * my_strcpy(char* dest, const char* src)
//const可以防止源字符串被改变
{
	assert( dest && src );
	char* ret = dest;
	while(*dest++ = *src++)
	{
		;
	}
	return ret;
}
int main()
{
	char arr1[20] = { 0 };
	char arr2[] = "hello";
 
	printf("%s\n", my_strcpy(arr1, arr2));
	return 0;
}