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How does C handle errors using errno and error codes?

How does C handle errors using errno and error codes? (Computer science one · POSIX Error Codes) — "Error Handling with a zero value results in an ERANGE error…

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Error handling uses error codes stored in errno
Standard error codes are defined in errno.h
ERANGE results when a zero value would require −∞, which C does not support as an actual number
EILSEQ indicates an illegal byte sequence in characters on systems that use UTF-8
Systems may define and support additional error codes
When an error occurs, a function sets the global variable errno to an error-code value
After a function returns, errno can be checked for an error code
Because error codes are integers, they are checked with the numerical comparison operator ==
A comparison of errno to zero checks for no error
The string library in string.h provides strerror(errno)
strerror(errno) maps errno to a human-readable error message

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How does C handle errors using errno and error codes?

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Computer science one

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"Error Handling with a zero value results in an ERANGE error as C does not support −∞ as an actual number. • EILSEQ indicates an illegal byte sequences in characters on systems that use UTF-8. All three of these are defined in the errno.h header file. Depending on the system, additional error codes may also be defined and supported (see POSIX Error Codes below). When an error occurs, a function will set the global variable errno to one of these error code values. Upon returning from a function, you can check for these error codes. Since these error codes are represented as integers, you simply use the numerical comparison operator, == . You can check for no error by making a comparison to zero. In addition, the standard string library, defined in the header file, string.h provides a function, char * strerror(errno) that can be used to map the value in errno to a human-readable error message. We discuss strings in detail later on, but we can see how to use this function in Code Sample"

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