Advice: The differences between cat and ||

There are two ways to join two strings together: with the cat function (e.g. cat(a,b) ) and with the || operator (e.g. a||b ). In many situations these have identical results, but there are two differences:

• The || operator does not evaluate its first argument. The other arguments are evaluated. The cat function, on the other hand, evaluates all its arguments. In the example below, evaluating a results in c . The first a in a||a||a is not evaluated, but all the other a 's are.

> a:= b: b:= c:

> a||a||a;

> cat(a,a,a);

• The result of the || operator is evaluated, while the result of cat is not evaluated. In the example below, evaluating cd results in ef . Recalling the unevaluated result of cat with % evaluates it.

> cd:= ef:

> c||d;

> cat(c,d);

> %;

See also:

cat , || operator , eval

Maple Advisor Database, R. Israel 1998