explain_strtoul(3)

💖 explain_strtoul(3) 💖

okay bestie, sit down, hydrate, and let me tell you about explain_strtoul — it lives in the Library Functions Manual and it's literally the friend who translates your cryptic error codes into actual sentences. ✨

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🌸 NAME 🌸

explain_strtoul — explain strtoul(3) errors

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🎀 SYNOPSIS 🎀

#include <libexplain/strtoul.h>
const char *explain_strtoul(const char *nptr, char **endptr, int base);
const char *explain_errno_strtoul(int errnum, const char *nptr, char
**endptr, int base);
void explain_message_strtoul(char *message, int message_size, const char
*nptr, char **endptr, int base);
void explain_message_errno_strtoul(char *message, int message_size, int
errnum, const char *nptr, char **endptr, int base);

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✨ DESCRIPTION ✨

These functions may be used to obtain explanations for errors returned by the strtoul(3) system call. Think of them as the group chat where your error finally gets the explanation it deserves. 💅

🦋 explain_strtoul 🦋

const char *explain_strtoul(const char *nptr, char **endptr, int base);

The explain_strtoul function is used to obtain an explanation of an error returned by the strtoul(3) system call. The least the message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail. it's giving detective energy fr fr 🔍

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

• nptr — The original nptr, exactly as passed to the strtoul(3) system call. no edits, no glow-up, just how you handed it over. 🫶
• endptr — The original endptr, exactly as passed to the strtoul(3) system call.
• base — The original base, exactly as passed to the strtoul(3) system call.

Returns: The message explaining the error. This message buffer is shared by all libexplain functions which do not supply a buffer in their argument list. This will be overwritten by the next call to any libexplain function which shares this buffer, including other threads.

⚠️ Note: This function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library. bestie. it is NOT. thread safe. 😭

Example: This function is intended to be used in a fashion similar to the following example:

unsigned long result = strtoul(nptr, endptr, base);
if (result < 0)
{
    fprintf(stderr, "%s\n", explain_strtoul(nptr, endptr, base));
    exit(EXIT_FAILURE);
}

The above code example is available pre‐packaged as the explain_strtoul_or_die(3) function. iconic, honestly. 👑

💜 explain_errno_strtoul 💜

const char *explain_errno_strtoul(int errnum, const char *nptr, char
**endptr, int base);

The explain_errno_strtoul function is used to obtain an explanation of an error returned by the strtoul(3) system call. The least the message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail.

• errnum — The error value to be decoded, usually obtained from the errno global variable just before this function is called. This is necessary if you 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. so if you dilly-dally, capture it FIRST. 🫵
• nptr — The original nptr, exactly as passed to the strtoul(3) system call.
• endptr — The original endptr, exactly as passed to the strtoul(3) system call.
• base — The original base, exactly as passed to the strtoul(3) system call.

Returns: The message explaining the error. This message buffer is shared by all libexplain functions which do not supply a buffer in their argument list. This will be overwritten by the next call to any libexplain function which shares this buffer, including other threads.

⚠️ Note: This function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library.

Example: This function is intended to be used in a fashion similar to the following example:

unsigned long result = strtoul(nptr, endptr, base);
if (result < 0)
{
    int err = errno;
    fprintf(stderr, "%s\n", explain_errno_strtoul(err, nptr,
    endptr, base));
    exit(EXIT_FAILURE);
}

The above code example is available pre‐packaged as the explain_strtoul_or_die(3) function.

🍓 explain_message_strtoul 🍓

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

The explain_message_strtoul function is used to obtain an explanation of an error returned by the strtoul(3) system call. The least the message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail.

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

• message — The location in which to store the returned message. If a suitable message return buffer is supplied, this function is thread safe. yes bestie, YOU brought the buffer, so now it's safe. slay. 💅
• message_size — The size in bytes of the location in which to store the returned message.
• nptr — The original nptr, exactly as passed to the strtoul(3) system call.
• endptr — The original endptr, exactly as passed to the strtoul(3) system call.
• base — The original base, exactly as passed to the strtoul(3) system call.

Example: This function is intended to be used in a fashion similar to the following example:

unsigned long result = strtoul(nptr, endptr, base);
if (result < 0)
{
    char message[3000];
    explain_message_strtoul(message, sizeof(message), nptr,
    endptr, base);
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

The above code example is available pre‐packaged as the explain_strtoul_or_die(3) function.

🧚 explain_message_errno_strtoul 🧚

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

The explain_message_errno_strtoul function is used to obtain an explanation of an error returned by the strtoul(3) system call. The least the message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail.

• 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 you 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. grab it early, bestie, or it's gone. 💀
• nptr — The original nptr, exactly as passed to the strtoul(3) system call.
• endptr — The original endptr, exactly as passed to the strtoul(3) system call.
• base — The original base, exactly as passed to the strtoul(3) system call.

Example: This function is intended to be used in a fashion similar to the following example:

unsigned long result = strtoul(nptr, endptr, base);
if (result < 0)
{
    int err = errno;
    char message[3000];
    explain_message_errno_strtoul(message, sizeof(message), err,
    nptr, endptr, base);
    fprintf(stderr, "%s\n", message);
    exit(EXIT_FAILURE);
}

The above code example is available pre‐packaged as the explain_strtoul_or_die(3) function.

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🌈 SEE ALSO 🌈

• strtoul(3) — convert a string to an unsigned long integer
• explain_strtoul_or_die(3) — convert a string to an unsigned long integer and report errors

iykyk, go read those next. 📚

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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, you ate that 🫶💖 and yeah — it's the explain_strtoul(3) page from the Library Functions Manual, so if anyone asks, you know exactly where you found it. mwah. 💅✨🌸