Is there a formula that will tell tell you the position of a specficic character in a text string

I would like to go one step further with this function.

1) find a specific chararter combination
ie
var text Temp = Left([my text field],"#%");
Length($Temp) +1
2) from the position where "#%" is located I like to read the next 5 characters
ie Mid([field], <start position>, 5)

if I replace <start position> with the two lines in 1) it doesn't work. I assume it has the do with the variable, the code in 1) or with the ;
Is there a better way to get this?

In an even better scenarion I should perhaps first check if the text string contains the value "#%"  at all to avoid wrong output of 1). Currently if it can't find it seems to result in the sting length  

did you try this

var text Temp = Left([my text field],"#%");
var number StartPosition = Length($Temp) +1;

Mid([field], $StartPosition, 5)

No I didn't.
But what I learn from this is how to define and use variables and that you can treat the formula field also as a field where we can enter pieces of code because that is what you actually doing.

And that opens new possibities, lots of them
What a joy :-)

for the second time today
TXS!!