algorithm for placing stock market orders

I'm trying to code a trading application as a project.

I'm stuck on placing orders part. If I try to place orders using if and while statements, order gets placed every time the condition is evaluated. E.g.,

while(ifstream<<9dayMovingAverage<<5dayMovingAverge){

if(9dayMovingAverage > 5dayMovingAverage){

goLong();
}
};

Is there any other way to do this?