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Function Details : regerror

size_tregerror(int errcode,const regex_t * preg,char * errbuf,size_t errbuf_size) ;

Return Type : size_t

Platform-specific unsigned type for array indices and memory sizes.
Read about return values of regerror function .

1st Parameter Type : int

Integer type (typically 4 bytes, -2,147,483,648 to 2,147,483,647)

1st Parameter

The error code returned by a previous regex function (e.g., `regcomp` or `regexec`).

2nd Parameter Type : const regex_t *

A pointer to a constant `regex_t` structure representing a compiled regular expression. The `const` qualifier ensures the structure cannot be modified through this pointer.

2nd Parameter

Pointer to the `regex_t` structure associated with the regex operation that produced the error.

3rd Parameter Type : char *

String pointer (array of characters)

3rd Parameter

Pointer to a buffer where the error message will be stored. Can be `NULL` to determine the required buffer size.

4th Parameter Type : size_t

Platform-specific unsigned type for array indices and memory sizes.

4th Parameter

The size of the buffer pointed to by `errbuf`.

Read more about parameters of regerror in parameters section
The regerrorfunction in C language Produces a human-readable error message based on the error code from regcomp or regexec.
The regerror function is used to generate a human-readable string describing the error code returned by regcomp or regexec. It's an essential part of error handling in regular expression operations.
The regerrorfunction takes 4 parameters:
  • •
    int `errcode`: The error code returned by a previous regex function (e.g., `regcomp` or `regexec`).
  • •
    const regex_t * `preg`: Pointer to the `regex_t` structure associated with the regex operation that produced the error.
  • •
    char * `errbuf`: Pointer to a buffer where the error message will be stored. Can be `NULL` to determine the required buffer size.
  • •
    size_t `errbuf_size`: The size of the buffer pointed to by `errbuf`.
Retrieves a human-readable error message corresponding to the `errcode` returned by a regex function. The error message is stored in the `errbuf` buffer, truncated if necessary to fit within `errbuf_size`. If `errbuf` is `NULL`, the function returns the size of the buffer required to hold the entire message. Returns the length of the error message, excluding the null terminator.
The regerror function return value :
  • Returns the size of the error message string, including the null terminator

Output

This example demonstrates how to use regerror to get a human-readable error message when regex compilation fails.