Hence it is necessary that each computer must have

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Unformatted text preview: Figure 12.7. As shown in the figure, the input to the compiler is the high-level language program (often referred to as a source program) and its output is the machine language program (often referred to as an object program). Since high-level language instructions are macro instructions, the compiler translates each highlevel language instruction into a set of machine language instructions rather than a single machine language instruction. Hence there is one-to-many correspondence between the high-level language instructions of a source program and the machine instructions of its equivalent object program. Note that during the process of translation of a source program into its equivalent object program by the compiler, the source program is not being executed. It is only being converted into a form that can be executed by the computer's processor. High-level language program -►input -►complier-►output-►Machine language program (Source Program) -► One-to-many correspondence-► (Object Program) A compiler can translate only those source programs, which have been written in the language for which the compiler is meant. For example, a FORTRAN compiler is only capable of translating source programs, which have been written in FORTRAN. Therefore, each computer requires a separate compiler for each high-level language that it supports. That is, to execute both FORTRAN and COBOL programs on a computer, this computer must have a FORTRAN compiler and a COBOL compiler. This is illustrated in Figure 12.8. Program PI in high-level language LI -►Compiler for language LI -► Machine code for PI Program P2 in high-level language L2 -►Compiler for language L2-► Machine code for P2 A computer supporting languages LI and L2 Figure 12.8. Illustrating the requirement of a separate compiler for each high-level language supported by a computer. Also note that an object program for one computer will not be the same as the object program for another computer. Hence it is...
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