字符串部分操作的函数实现

#include <iostream>
using namespace std;

/*
求sub字符串在src中匹配的位置，匹配失败返回-1
*/
int findStr(const char*src,const char*sub)
{
if(src==NULL || sub==NULL)
return -1;
const char * srcp;
const char * subp;
int index=-1;
while(*src!=0)
{
index++;
srcp=src++;
subp=sub;
while(*srcp++==*subp++)
{
if(*subp==0)
return index;
}
}
return -1;
}
/*
字符串翻转
*/
void revStr(char* str)
{
if(str==NULL)
return;
int length=strlen(str);
int midIndex=(length%2==0)?(length/2):(length/2+1);
for(int i=0;i<midIndex;++i)
{
char temp=str[i];
str[i]=str[length-i-1];
str[length-i-1]=temp;
}
}
/*
判断是否是回文
*/
bool isHuiWen(const char *str)
{
int length=strlen(str);
int midIndex=length/2;
bool huiWen=true;
for(int i=0;i<midIndex;i++)
{
if(str[i]!=str[length-i-1])
{
huiWen=false;
break;
}
}
return huiWen;
}
/*
字符串的比较，前者大返回1，后者大返回-1，相等返回0
*/
int myStrCmp(const char* src,const char * dst)
{
int ret=0;
while( !(ret=*src-*dst) && *dst)
{
src++;
dst++;
}
if(ret>0)
ret=1;
else if(ret<0)
ret=-1;
return ret;
}
/*
获取字符串长度,这种方法在求长字符串时较快速
*/
int getStrLen(const char *str)
{
const char *temp=str;
while(*str++!=0);
return str-temp-1;
}
int main()
{
cout<<findStr("chen","he")<<endl;

char str1[]="hello";
revStr(str1);
cout<<str1<<endl;

cout<<isHuiWen("hello")<<endl;
cout<<isHuiWen("chehc")<<endl;

cout<<myStrCmp("chen","chen")<<endl;
cout<<myStrCmp("che","chen")<<endl;
cout<<myStrCmp("chen","che")<<endl;

cout<<getStrLen("chen")<<endl;
return 0;
}