about member variable

[jayjay60]

In my app i declare a pointer as a member variable(double *pTab. This pointer will be used as a pointer on an array of double. In one of the member function, i want to do some calculation which do affectation like that:
for(i=1;i<=n;i++)
{
*(pTab+i)=Value_i;
}
I don't want that this function return value so i decide it will be type &quot;void&quot;.
And now i want to use this function in another member method. So, if i call the first function, i would like to know if i will be able to get one of specific value of the array.

For example, could i just return the value *(pTab+i2)?

thanks in advance for your help

jayjay

 

[Zyrenthian]

you would need to change your function from void to return a double but yes you can do that.

Matt

 

[jayjay60]

Do you mean that my first function haev to be changed from &quot;voi&quot; to &quot;double&quot;?

 

[Zyrenthian]

yes... for example:

// old funciton

void foo()
{
// for loop

}

// new function

double foo()
{
// loop til value found
return *(pTab+i2);

}


the alternative is passing in a argument by reference and setting that to keep the function a void function.

Matt

 

[jayjay60]

Could you eplain more your last sentence?

gerald

 

[StukA]

What he means is that you could add a new parameter to your function of the form double &x. This is a &quot;pass by reference&quot; parameter, which means that changes to the variable inside the function will be reflected in the originally passed variable. For example:

void myFunc(double &x){
//other code here
for(i=1;i<=n;i++)
{
*(pTab+i)=Value_i;
}
x = *pTab;
}

When this function returns, whatever variable you passed in as the 'x' parameter will contain the value pointed to by pTab at the end of the loop.

 

[fheyn]

one remark to &quot;returning by reference&quot;:
it makes a program much more readable if a function returns a value through its type - declaration.
&quot;passing by reference&quot; is OK, but after a few weeks or months you won't know if your function just received a
parameter or also gave something back if it returned some
value by reference.
By the way, you'll see many functions getting their parameters as 'const';