Now to fulfil a promise made earlier about what a register variable is. A computer can keep data in a register or in a memory. A register is much faster in operation than memory but there are very few registers available for the programmer to use. If there are certain variables that are used extensively in a program, you can designate that those variables are to be stored in a register if possible in order to speed up the execution of the program. Depending on the computer and the compiler, a small number of register variables may be allowed and are a desired feature.
Check your compiler documentation for the availability of this feature and the number of register variables. Most compilers that do not have any register variables available, will simply ignore the word "register" and run normally, keeping all variables in memory.
Register variables are only available for use with integer and character type variables. This may or may not include some of the other integer-like variables such as unsigned, long, or short. Check the documentation for your compiler.
Register variables are allowed in HiTech C, with up to four non-pointer register variables (in 68000 registers D4 to D7), and up to three pointer register variables (in A3 to A5). This usage does not conflict with the 1616/OS usage of D0 to D2 and A0 to A2). As MS-DOS compilers typically only allow two register variables, many programmers do not make extensive use of register variables, so you can often gain a little extra speed when converting programs by a wider use of register variables (the compiler will ignore the register variable request if no registers are available, and treat the variable as an ordinary one).
Check your compiler documentation for the availability of this feature and the number of register variables. Most compilers that do not have any register variables available, will simply ignore the word "register" and run normally, keeping all variables in memory.
Register variables are only available for use with integer and character type variables. This may or may not include some of the other integer-like variables such as unsigned, long, or short. Check the documentation for your compiler.
Register variables are allowed in HiTech C, with up to four non-pointer register variables (in 68000 registers D4 to D7), and up to three pointer register variables (in A3 to A5). This usage does not conflict with the 1616/OS usage of D0 to D2 and A0 to A2). As MS-DOS compilers typically only allow two register variables, many programmers do not make extensive use of register variables, so you can often gain a little extra speed when converting programs by a wider use of register variables (the compiler will ignore the register variable request if no registers are available, and treat the variable as an ordinary one).
