Get a function to update a passed variable?

hi everyone,

i've written little function accepts few inputs.  it works great...except, variables pass function don't have value updated when function runs.

this simplified version of code:

code: [select]

//
// application variables
//

unsigned int intwatertemperature_counter = 0;

//
// application setup
//
void setup() {
 // configure serial output
 serial.begin(9600);

 // start stream carriage return
 serial.println();
}

// application loop
void loop(){

 serial.print(countertest(intwatertemperature_counter));
 serial.print(",");
 serial.println(intwatertemperature_counter);
 delay(500);
}

int countertest(unsigned int thissamplecounter){
 thissamplecounter++;
 return thissamplecounter;
}


the output receive is:
[font=courier]1,0
1,0
1,0
1,0[/font]

i expect receive more like:
[font=courier]1,1
2,2
3,3
4,4[/font]

i know simple, don't understand why doesn't work.  i'm vb dot net programming land!

any appreciated.

cheers,
scott  

what assume happening, parameter function countertest, being initialised new variable every execution.  how make function accept existing variable parameter?

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