Linux系统下C语言练习:指针实现mystrcmp、mystrlen

Linux系统下C语言练习:指针实现mystrcmp、mystrlen

#include
#include

char *mystrcmp(char *str, char *str1)
{
	while(*(str++) - *(str1++) == 0 && *str != '\0' && *str != '\0');
	char *p1 = "第一个数小于第二个数";
	char *p2 = "第一个数大于第二个数";
	char *p3 = "第一个数等于第二个数";

	str--;
	str1--;
	if((*str - *str1) == 0 && (*(str + 1) =='\0') && (*(str1 + 1) != '\0'))
	{
		return p1;
	}
	
	if((*str - *str1) == 0 && (*(str1 + 1) =='\0') && (*(str + 1) != '\0'))
	{
		return p2;
	}
	if((*str - *str1) == 0 && (*(str1 + 1) =='\0') && (*(str + 1) == '\0'))
	{
		return p3;
	}
	if(*str - *str1 < 0)
	{
		return p1;
	}	
	if(*str - *str1 > 0)
	{
		return p2;
	}	
}

int mystrlen(char *p)
{
	int count = 0;
	while(*p++ !='\0') 
	count++;
	return count;
}

int main()
{
	printf("请输入两串字符\n");
	char *str = (char *)malloc(sizeof(char) * 20);
	char *str1 = (char *)malloc(sizeof(char) * 20);
	if(NULL == str || NULL == str1)
	{
		printf("error\n");
		exit(1);
	}
	scanf("%s%s", str, str1);	
	printf("第一个字符串长度为:%d\n", mystrlen(str));
	printf("第二个字符串长度为:%d\n", mystrlen(str1));
	printf("%s\t%s\n", str,str1);
	printf("%s\n", mystrcmp(str, str1));
	
	free(str);
	free(str1);
	return 0;
}