Adds the string representation of the given object as the next parameter.

Gets the i'th parameter value.

Parameter numbers start at 1.

Substitutes substrings of the given string.

Substitutions are in three forms:

• $i
• ${[chars]i[chars]}
• $i?then[:else]

where i is a digit in the range [1,9] and refers to the value of the ith parameter, chars may be any characters except [1-9}], and then and else are of one of the two forms:

• j
• {[chars j chars k chars ...]}

where j is likewise a digit in the range [1,9] and refers to the value of the jth parameter.The first substitution form replaces $i with the value of the ith parameter.The second form replaces everything from the $ to the } with the contents of the {} where i is replaced with the value of the ith parameter. However, if the value is empty, then everything from the $ to the } is instead erased.For example, ${"1": } will substitute the value of the 1st parameter quoted followed by a : and a space if non-empty; if empty, then everything from the $ to the } will instead be erased.The third form tests the value of the ith parameter: if non-empty, then the then portion is substituted; if empty, then the else portion is. Both the then and else portions can be either a digit in the range [1,9] or chars enclosed by {}. The {} here can contain multiple parameter indicies. If at least one is non-empty, then the substitution for the portion will be done; if all are empty, then everything for the portion will be erased.The \ character can be used to escape the meaning of the $, [1-9], ?, :, and } characters and instead treat them as ordinary characters.Substitution is performed by making at most 9 passes over the string, one pass per parameter starting at 1. Substitutions may themselves have further substitutions, but, due to the way that substitution is performed, should only refer to parameters having higher digits. (Digits less than or equal to the current one will not be substituted.)