C和指針 04

#include <iostream>
using namespace std;


//查找子字符串 並返回第一個字母
char* find_char( char* source,  char* chars)  //這裏主要因爲賦值 所以沒有使用const
{
    char* p = source;
char* q = chars;
while(*p != NULL)
{
if(*p != *q)  //將if語句提取到外面 效率更高
{
p++;
source++;
}
else
{
while(*q != NULL)
{
if(*p == *q)
{
p++;
q++;
}
}
if(*q == NULL)
break;
else
{
q = chars;
p = ++source;
}
}
}
if(*source == NULL)
return NULL;
return source;
}




int del_substr(char *str,  char* substr)  //在裏面找到就返回1  不在返回0
{
char *p = str;
char *q = substr;
int len = strlen(substr);
char *index = find_char(p, q);
if(*index == NULL)
{
cout<<"the substr isn't in the str"<<endl;
return 0;
}
else
{
while(*p  != NULL && p != index)
p++;  //獲取位置
char *q = p+len;
while(*q != NULL)
{
   p = q;
q++;
p++;
}
}
return 1;
}




void reverse_string(char* str)  //進行字符串的反轉
{
int len = strlen(str);
char *p = str;
char *q = str+len-1;
char ch;
while(p < q)
{
ch = *p;
*p++ = *q;
*q-- = ch;
}
}




int main()
{
//其實在這裏還是需要判斷下的 總不能對NULL取指針吧。。。。
char *p = "SmithJackji";
char *q = "Jack";

cout<<del_substr(p,q)<<endl;

char p[]= "Smith";

reverse_string(p);  
return 0;
}