STRCMP(3POSIX)

💖 STRCMP(3POSIX) 💖

okay bestie, welcome to the POSIX Programmer's Manual ✨ this one's filed under STRCMP(3POSIX) and honestly it's a whole classic.

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🌸 PROLOG 🌸

okay so first things first, real talk: this manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ — so like, go check the corresponding Linux manual page if you wanna know how Linux actually does it, bestie. Or… the interface may not be implemented on Linux at all. 🙈 iykyk.

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✨ NAME ✨

strcmp — compare two strings 💅

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🎀 SYNOPSIS 🎀

#include <string.h>

int strcmp(const char *s1, const char *s2);

she's simple, she's iconic, she takes two const char * and hands you back an int. no cap.

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🦋 DESCRIPTION 🦋

so the functionality described on this reference page is aligned with the ISO C standard. If there's any conflict between the requirements described here and the ISO C standard, that conflict is unintentional — not a vibe, just an accident. This volume of POSIX.1‐2017 defers to the ISO C standard. periodt.

The strcmp() function shall compare the string pointed to by s1 to the string pointed to by s2.

The sign of a non-zero return value shall be determined by the sign of the difference between the values of the first pair of bytes (both interpreted as type unsigned char) that differ in the strings being compared. like, the literal first moment they stop matching? that's the one that decides everything. main character energy fr fr.

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🔥 RETURN VALUE 🔥

Upon completion, strcmp() shall return an integer:

• greater than 0 — if the string pointed to by s1 is greater than the string pointed to by s2
• equal to 0 — if the string pointed to by s1 is equal to the string pointed to by s2
• less than 0 — if the string pointed to by s1 is less than the string pointed to by s2

in that order, respectively. she ate 💅

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💀 ERRORS 💀

No errors are defined.

The following sections are informative.

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🌈 EXAMPLES 🌈

🍓 Checking a Password Entry

okay so this example is giving security vibes. The following example compares the information read from standard input to the value of the name of the user entry. If the strcmp() function returns 0 (indicating a match), a further check will be made to see if the user entered the proper old password. The crypt() function shall encrypt the old password entered by the user, using the value of the encrypted password in the passwd structure as the salt. If this value matches the value of the encrypted passwd in the structure, the entered password oldpasswd is the correct user's password. Finally, the program encrypts the new password so that it can store the information in the passwd structure. obsessed honestly.

#include <string.h>
#include <unistd.h>
#include <stdio.h>
...
int valid_change;
struct passwd *p;
char user[100];
char oldpasswd[100];
char newpasswd[100];
char savepasswd[100];
...
if (strcmp(p->pw_name, user) == 0) {
    if (strcmp(p->pw_passwd, crypt(oldpasswd, p->pw_passwd)) == 0) {
        strcpy(savepasswd, crypt(newpasswd, user));
        p->pw_passwd = savepasswd;
        valid_change = 1;
    }
    else {
        fprintf(stderr, "Old password is not valid\n");
    }
}
...

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🧚 APPLICATION USAGE 🧚

None.

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👑 RATIONALE 👑

None.

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🫶 FUTURE DIRECTIONS 🫶

None.

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💜 SEE ALSO 💜

• strncmp()
• The Base Definitions volume of POSIX.1‐2017, <string.h>

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⭐ COPYRIGHT ⭐

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .

not the "referee document" 💀 okay but fr fr if anything disagrees, the original IEEE and The Open Group Standard wins. no notes.

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and that's the whole page bestie!! 🎀 brought to you by IEEE/The Open Group, 2017, on a STRCMP(3POSIX) footer tip — stay hydrated, keep your strings null-terminated, mwah 💖✨