void CTestTmp123Dlg::OnButton1()
{
char charar1[] = "I have an apple, aaa, aabb, abb", charar2[] = "abb", *p;
int intPosition;
// 下面四行用C的库函数，没找到返回-1
if (p = strstr(charar1, charar2))
intPosition = (p - charar1);
else
intPosition = -1;

// 下面四行用VC++的库函数，没找到返回-1
intPosition = CString(charar1).Find(charar2);

// 下面是自己写的不用任何库函数的方法，没找到返回-1
intPosition = StrStr(charar1, charar2);
}

int CTestTmp123Dlg::StrStr(char charar1[], char charar2[])
{
int intCheckStart, intState;
for (intCheckStart = 0; intCheckStart < strlen(charar1)-strlen(charar2); intCheckStart++)
{
intState = 0;
while (charar1[intCheckStart+intState] == charar2[intState] && intState < strlen(charar2))
intState++;
if (intState == strlen(charar2)) // find the match
return intCheckStart;
}
return -1;
}

以下c++代码在vc++6.0 中可正确运行
#include <iostream.h>
#include "string.h"
char charar1[] = "aaabb,abb", charar2[] = "abb";
int f(char a[],char b[])
{int l1=strlen(a),l2=strlen(b),i,j,i0,c=0;
for(i=0;i<=l1-l2;i++)

{c=0;
for(i0=i,j=0;j<l2;j++)
if(a[i]==b[j])
{i++;
c++;}
i=i0;
if(c==l2)
{
return i;
}
}
return -2;//找不到返回-2
}
void main()
{cout<<f(charar1,charar2)<<endl;
}