Index checking means that, in all expressions indexing an array, the index value is checked against the bounds of the array (which were established when the array was defined), and if the index is out-of-bounds, further execution is suspended via some sort of error. Because using a number outside of the upper range in an array may cause the program to crash, or may introduce security vulnerabilities (see buffer overflow), index checking is a part of many high-level languages.
Pascal, Fortran, Java have index checking ability. The VAX computer has an INDEX assembly instruction for array index checking which takes six operands, all of which can use any VAX addressing mode. The B6500 and similar Burroughscomputers performed bound checking via hardware, irrespective of which computer language had been compiled to produce the machine code. A limited number of later CPUs have specialised instructions for checking bounds, e.g., the CHK2 instruction on the Motorola 68000 series.
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Cumberland Computer Services., LLC
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https://cumberlandcomputerservices.com/
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