I'm sorry for my English. I look for tool or script for combining text fields in this way: e.g.
field_1 (contains 3 to 6 signs)
field_2 (contains 6 to 10 signs)
[field_1] & x & [field_2]
where x = variable number of signs (e.g. "-" or "0") which will give me globally always 25 characters as a result of combining. I'm working in arcgis or qgis. It could be also tool in acces or excel.