求解释啊，为何觉得IF没一点作用

你的B[10]数组在执行完次循环后未重新设置初值。
void fun()
{
    int one,two,three;
    int b[10]={0,0,0,0,0,0,0,0,0,0};
    for(one=123;one<=333;one++)
    {
        three=3*one;
        two=2*one;
        if(one%10!=0&&one/10%10!=0&&one/100!=0&&two%10!=0&&two/10%10!=0&&two/100!=0&&three%10!=0&&three/10%10!=0&&three/100!=0)
        {
            b[(one%10)]=one%10;
            b[(one/100)]=one/100;
            b[((one/10)%10)]=((one/10)%10);
            b[(two%10)]=two%10;
            b[((two/10)%10)]=(two/10)%10;
            b[(two/100)]=two/100;
            b[(three%10)]=three%10;
            b[((three/10)%10)]=(three/10)%10;
            b[(three/100)]=three/100;
            if(b[0]==0&&b[1]==1&&b[2]==2&&b[3]==3&&b[4]==4&&b[5]==5&&b[6]==6&&b[7]==7&&b[8]==8&&b[9]==9)
                cout<<one<<" "<<two<<" "<<three<<" "<<"符合条件"<<endl;
            b[0]=0；
            b[1]=0；
            b[2]=0；
            b[3]=0；
            b[4]=0；
            b[5]=0；
            b[6]=0；
            b[7]=0；
            b[8]=0；
            b[9]=0；            
        }
    }
}
不知对否未验证！

得不到你想要的结果，得到的值也不确定。