It is not that some languages have jobs and others do not have, C is a very good language one can understand the concepts of computer science by working on C language. There are jobs in C also but some high level projects. However languages like php can get you jobs easily as these are used in web development work and today people with even small business have websites. But knowledge is the king in computer science, if one has good understanding of languages like C one can deliver quality work irrespective of the language one works may it be php.