explain_strtod(3)

💖 explain_strtod — bestie, let's decode ur strtod(3) errors 💖

okay so real talk: this is explain_strtod(3) from the Library Functions Manual, and it's literally the glow-up ur error messages have been begging for. no cap.

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✨ NAME ✨

explain_strtod — explain strtod(3) errors 🫶

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✨ SYNOPSIS ✨

#include <libexplain/strtod.h>
const char *explain_strtod(const char *nptr, char **endptr);
const char *explain_errno_strtod(int errnum, const char *nptr, char
**endptr);
void explain_message_strtod(char *message, int message_size, const char
*nptr, char **endptr);
void explain_message_errno_strtod(char *message, int message_size, int
errnum, const char *nptr, char **endptr);

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✨ DESCRIPTION ✨

so these functions? they're the ones u call to get actual explanations for errors handed back by the strtod(3) system call. not just "something broke lol" — like, the why. 💅

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🌸 explain_strtod 🌸

const char *explain_strtod(const char *nptr, char **endptr);

explain_strtod is ur girl for getting an explanation of an error that strtod(3) returned. the absolute least the message will contain is the value of strerror(errno), but bestie, usually it does so much better and points at the actual underlying cause in more detail. it's giving detective energy. 🔍

the errno global variable gets used to grab the error value that needs decoding.

• nptr — the original nptr, exactly as it was passed to the strtod(3) system call. no edits, no vibes-based reinterpretation.
• endptr — the original endptr, exactly as it was passed to the strtod(3) system call.

Returns: the message explaining the error. heads up tho — this message buffer is shared by every libexplain function that doesn't supply a buffer in its own argument list. it will get overwritten by the very next call to any libexplain function that shares this buffer, including other threads. 😭

Note: this function is not thread safe, because it shares a return buffer across all threads — and ngl, so do many other functions in this library. not me warning u twice. 🚩

Example: this function is meant to be used in a fashion similar to this:

double result = strtod(nptr, endptr);
if (result < 0)
{
    fprintf(stderr, "%s\n", explain_strtod(nptr, endptr));
    exit(EXIT_FAILURE);
}

the code example above is available pre-packaged as the explain_strtod_or_die(3) function. iconic behavior, honestly. 👑

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🦋 explain_errno_strtod 🦋

const char *explain_errno_strtod(int errnum, const char *nptr, char
**endptr);

explain_errno_strtod does the same cute thing — explains an error returned by the strtod(3) system call. again, the least the message will contain is the value of strerror(errno), but usually it goes way harder and shows u the underlying cause in more detail. 💜

• errnum — the error value to be decoded, usually grabbed from the errno global variable right before this function gets called. this is necessary if u need to run any code between the system call being explained and this function, because bestie, many libc functions will alter the value of errno. it's not loyal. 😭
• nptr — the original nptr, exactly as passed to the strtod(3) system call.
• endptr — the original endptr, exactly as passed to the strtod(3) system call.

Returns: the message explaining the error. same deal as before: this buffer is shared by all libexplain functions that don't supply their own buffer, and it gets clobbered by the next call to any libexplain function sharing it, including from other threads.

Note: not thread safe either, for the exact same shared-buffer reason. and yeah, many other functions in this library are like this too. 🙈

Example: meant to be used in a fashion similar to:

double result = strtod(nptr, endptr);
if (result < 0)
{
    int err = errno;
    fprintf(stderr, "%s\n", explain_errno_strtod(err, nptr,
    endptr));
    exit(EXIT_FAILURE);
}

and yes, the code example above is available pre-packaged as the explain_strtod_or_die(3) function. ✨

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🎀 explain_message_strtod 🎀

void explain_message_strtod(char *message, int message_size, const char
*nptr, char **endptr);

explain_message_strtod gets u an explanation of an error returned by the strtod(3) system call. least it'll contain is strerror(errno), but usually it's way more helpful and tells u the underlying cause in detail. the way that it just knows things. 🔮

errno is the global variable used to obtain the error value to be decoded.

• message — where to store the returned message. if u supply a suitable message return buffer, this function is thread safe. slay.
• message_size — the size in bytes of the location where the returned message gets stored.
• nptr — the original nptr, exactly as passed to the strtod(3) system call.
• endptr — the original endptr, exactly as passed to the strtod(3) system call.

Example: meant to be used in a fashion similar to:

double result = strtod(nptr, endptr);
if (result < 0)
{
    char message[3000];
    explain_message_strtod(message, sizeof(message), nptr,
    endptr);
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

the code example above? pre-packaged as the explain_strtod_or_die(3) function. periodt. 💅

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🌈 explain_message_errno_strtod 🌈

void explain_message_errno_strtod(char *message, int message_size, int
errnum, const char *nptr, char **endptr);

explain_message_errno_strtod — same mission, explains an error returned by the strtod(3) system call. the least the message will contain is the value of strerror(errno), but usually it does much better and indicates the underlying cause in more detail. main character energy fr fr. 👑

• message — the location in which to store the returned message. if a suitable message return buffer is supplied, this function is thread safe. 🫶
• message_size — the size in bytes of the location in which to store the returned message.
• errnum — the error value to be decoded, usually obtained from the errno global variable just before this function is called. this is necessary if u need to call any code between the system call to be explained and this function, because many libc functions will alter the value of errno. keep an eye on it bestie, it wanders. 👀
• nptr — the original nptr, exactly as passed to the strtod(3) system call.
• endptr — the original endptr, exactly as passed to the strtod(3) system call.

Example: meant to be used in a fashion similar to:

double result = strtod(nptr, endptr);
if (result < 0)
{
    int err = errno;
    char message[3000];
    explain_message_errno_strtod(message, sizeof(message), err,
    nptr, endptr);
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

and obviously, the code example above is available pre-packaged as the explain_strtod_or_die(3) function. ate. 🔥

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✨ SEE ALSO ✨

• strtod(3) — convert ASCII string to floating-point number
• explain_strtod_or_die(3) — convert ASCII string to floating-point number and report errors

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✨ COPYRIGHT ✨

libexplain version 1.4 Copyright (C) 2009 Peter Miller

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okay that's the whole page bestie, ur officially a strtod(3) error-decoding icon now 💖✨🦋 the vibe check is passed, the docs are slayed, and this was explain_strtod(3) from libexplain version 1.4, Copyright (C) 2009 Peter Miller — mwah, go forth and debug 💅🎀