算法练习Mystrstr
草稿hello wolrd
hxl
if(*pFirst == *pFindFirst)
pFirst ++;
pFindFirst ++;
if(*pFirst == *pFindFirst)
pFirst ++;
pFindFirst ++;
for(int i ; i < strlen(hello wolrd) ; i++)
{
if(*pFindFirst == '\0')
return 0;
if(*pFirst == *pFindFirst)
{
pFirst++;
pFindFirst++;
count ++;
if(count == strlen(hel))
return pFirst - count;
continue;
}else
{
count = 0;
pFindFirst = findstr;
pFirst++;
}
}
return 0;
于是有了下面代码
#include <stdio.h>
#include <Windows.h>
size_t mystrlen(const char* str)
{
return (NULL == str || *str =='\0') ? 0 : mystrlen(str+1) + 1;
}
char* mystrstr(const char* Srcstr, const char* findstr)
{
if(Srcstr == NULL || findstr == NULL || *Srcstr == '\0' ||*findstr == '\0')
return NULL;
const char *pFindFirst = findstr;
const char* pFirst = Srcstr;
int count = 0;
int findstrlen = mystrlen(findstr);
int srclen = mystrlen(Srcstr);
for(int i = 0 ; i < srclen ; i++)
{
if(*pFindFirst == '\0')
return NULL;
if(*pFirst == *pFindFirst)
{
pFirst++;
pFindFirst++;
count ++;
if(count == findstrlen)
return (char*)(pFirst - count);
continue;
}else
{
count = 0;
pFindFirst = findstr;
pFirst++;
}
}
return NULL;
}
void main()
{
EX:
char *str = (char*)malloc(250);
char *findstr = (char*)malloc(250);
memset(str,'\0',250);
memset(findstr,'\0',250);
printf("input src string :");
gets(str);
printf("\ninput find string :");
gets(findstr);
printf("\n");
char* pRetstr = mystrstr(str, findstr);
if(pRetstr != NULL)
printf("find string is :%s\n",pRetstr);
else
printf("no find!\n");
printf("ExitProcess ? Y # N\n");
memset(str,'\0',250);
gets(str);
if(*str == 'n' || *str == 'N')
goto EX;
else
{
free(str);
free(findstr);
ExitProcess(0);
}
}
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