In c language can the first letter of the identifier be underscores state true or false

true

Explanation:

Overall the answer to this question would be yes, since the only rules for naming identifiers are that it must only be made up of alphanumerical values and/or underscore. Therefore, as long as it meets this rule it is completely valid. That being said C coders tend to stay away from this practice as it may cause errors in some situations due to interfering with some system names depending on what identifier name is being used.