C语言之strstr函数

【FROM MSDN && 百科】

原型：char *strstr(const char *str1, const char *str2);

#include

找出str2字符串在str1字符串中第一次出现的位置（不包括str2的串结束符）。返回该位置的指针，如找不到，返回空指针。

Returns a pointer to the first occurrence of strSearch in str, or NULL if strSearch does not appear in str. If strSearch points to a string of zero length, the function returns str.

DEMO: mystrstr

#include 
#include 
#include 
#include 
#pragma warning (disable:4996)
char *mystrstr(char *s1,char *s2);
int main(void)
{
	char *s="Golden Global View";
	char *l="ob";   //char *l=""
	char *p;
	system("cls");
	p=mystrstr(s,l);
	if (p!=NULL)
	{
		printf("%s\n",p);
	}
	else
	{
		printf("Not Found!\n");
	}
    getch();
	return 0;
}
/*FROM 百科*/
char *mystrstr(char *s1,char *s2)
{
	int n;
	if (*s2)                      //两种情况考虑
	{
        while(*s1)               
		{
            for (n=0;*(s1+n)==*(s2+n);n++)
            {
				if (!*(s2+n+1))            //查找的下一个字符是否为'\0'
				{
					return (char*)s1;
				}
            }
			s1++;
		}
		return NULL;
	}
	else
	{
		return (char*)s1;
	}
}

DEMO:

//#define FIRST_DEMO
#define SECOND_DEMO

#ifdef FIRST_DEMO
#include 
#include 
#include 
int main(void)
{
	char *s="Golden Global View";
	char *l="lob";
	char *p;
	system("cls");
	p=strstr(s,l);
	if (p!=NULL)
	{
		printf("%s\n",p);
	}
	else
	{
		printf("Not Found!\n");
	}

	getch();
	return 0;
}
#elif defined SECOND_DEMO
/*从字串” string1 onexxx string2 oneyyy”中寻找”yyy”*/
#include 
#include 
#include 
int main(void)
{
	char *s="string1 onexxx string2 oneyyy";
	char *p;
	p=strstr(s,"string2");
	printf("%s\n",p);
	if (p==NULL)
	{
		printf("Not Found!\n");
	}
	p=strstr(p,"one");
	printf("%s\n",p);
	if (p==NULL)
	{
		printf("Not Found!\n");
	}
	p+=strlen("one");
	printf("%s\n",p);

	getch();
	return 0;
}
#endif