C语言字符函数与字符串函数详解

	char arr[] = "abcdef";
	//错误示范
	int sz1 = strlen(arr);
	//正确示范
	size_t sz = strlen(arr);

//3 - 8 < 0?
//strlen函数是size_t类型，是无符号的，必定大于0！！！
int main()
{
	if (strlen("abc") - strlen("abcdefgh") > 0)
	{
		printf("哈哈哈~~");
	}
	else
		printf("吼吼吼！");
	return 0;
}
//运行结果是   哈哈哈~~

int main()
{
	if ((int)strlen("abc") - (int)strlen("abcdefgh") > 0)
	{
		printf("哈哈哈~~");
	}
	else
		printf("吼吼吼！");
	return 0;
}
//运行结果是   吼吼吼！

	//错误示范
	//目标字符串空间太少
	char arr1[] = "xxx";
	char arr2[] = "hello\0abc";
	strcpy(arr1, arr2);

#include<stdio.h>
#include<assert.h>
void* my_strcpy(char* dest, const char* src)
{
	assert(dest && src);
	char* ret = dest;
	while (*src)
	{
		*dest = *src;
		dest++;
		src++;
	}
	*dest = '\0';
}
int main()
{
	char arr1[] = "xxxxxxxxxxxxxxxx";
	char arr2[] = "abc";
	my_strcpy(arr1, arr2);
	printf("%s", arr1);
	return 0;
}

#include<stdio.h>
#include<assert.h>
char* my_strcpy(char* dest, const char* src)
{
	assert(dest && src);
	char* ret = dest;
	while (*dest++ = *src++)
	{
		;
	}
	return ret;
}
int main()
{
	char arr1[] = "xxxxxxxxxxxxxxxx";
	char arr2[] = "abc";
	printf("%s", my_strcpy(arr1, arr2));
	return 0;
}