判断一个串B位于串A的位置

int main (void){
char* A = "abcdefgee";
char* B = "bcdefg";
printf("match at %d
",bf(A,B));
return 0;
}

int bf (const char* _A,const char* _B){
int m,n,i,j;
    m = strlen (_A);
    n = strlen (_B);
    i = 0;
    j = 0;
    while(i<m && j<n)
    {
        if(_A[i] == _B[j])
        {
            printf("OK %d %d %c %c
",i,j,_A[i],_B[j]);
            i++;
            j++;
        }
        else
        {
            printf("OK %d %d %c %c
",i,j,_A[i],_B[j]);     
            i = i-j+1;j=0;
        } 
    }
    if( j>=n ) 
        return i-n;
    else 
        return 0; 
}