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For-loops (which have a fixed iteration limit) are a special case of while-loops. A function which can be implemented using only for-loops is called primitive recursive. (In contrast, a Computable Function can be coded using a combination of for- and while-loops, or while-loops only.)
The Ackermann Function is the simplest example of a well-defined Total Function which is Computable but not primitive recursive, providing a counterexample to the belief in the early 1900s that every Computable Function was also primitive recursive (Dötzel 1991).
See also Ackermann Function, Computable Function, Total Function
References
Dötzel, G. ``A Function to End All Functions.'' Algorithm: Recreational Programming 2, 16-17, 1991.