Concatenate two strings
Remarks
concat/3 works as if defined by the equation
String3 = String1 + String2
Example
concat("aaa","bbb",X) X=aaabbb 1 Solution concat("aaa",X,"aaa----bbb") X=----bbb 1 Solution concat(X,"bbb","aaa----bbb") X=aaa---- 1 Solution concat("aaa","bbb","aaabbb") Yes concat("aaa","bbb","aaa----bbb") No