... ANSI standard has made many small changes and additions to basic types and expressions. There are nowsigned and unsignedforms of all integer types, and notationsfor unsigned constants and hexadecimal ... externalvariablesatthebeginningofthesourcefile, and thenomitallexterndeclarations.If the program is in several source files, and a variable is defined in file1 and used in file2 and file3, thenexterndeclarations are needed in file2 and file3 to connect the occurrences of thevariable. ... variable, and that areunlikely to get mixed up typographically. We tend to use short names for local variables,especiallyloopindices, and longernamesforexternalvariables. 2. 2DataTypes and SizesThereareonlyafewbasicdatatypesinC:charasinglebyte,capableofholdingonecharacterinthelocalcharactersetintaninteger,typicallyreflectingthenaturalsizeofintegersonthehostmachinefloatsingle-precisionfloatingpointdoubledouble-precisionfloatingpointIn...