Programming Evolution

Higher-Level Languages

• A high-level language (HLL) was another big step up in programming; higher level of abstraction
• Uses a compiler—a program that translates a high-level language into machine code
• Some compilers translate HLL into assembly language and then use the assembler to translate into machine code; translating vs. compiling
• FORTRAN and COBOL were early high-level languages. Now adding two numbers would be something like: ADD GrossPay TO YearToDateGross
• The compiler takes care of changing the English-like statements into machine language (e.g. load YearToDateGross into a register, add GrossPay to the register, store the contents of the register in YearToDateGross) This is the concept of abstraction
• More human-friendly; some languages read more like English than others (e.g. Macintosh HyperCard)
• Machine independent—if you wrote a program in C++ on a UNIX machine, you should be able to take the source code and compile it on a Pentium.

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