strcmp(3)

💖 strcmp(3) — the "are these two strings the same??" girlie 💖

okay bestie, so this is strcmp, a lil function from the Library Functions Manual (section 3, we love a library function era ✨). It's literally just comparing strings and we're gonna talk about it for a while, strap in 🎀

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🌸 NAME 🌸

strcmp — strings compare 💅 (yes that's the actual name, "strings compare", iconic brevity fr fr)

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📚 LIBRARY 📚

Standard C library — aka libc, and you link it with -lc 🫶

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✨ SYNOPSIS ✨

#include <string.h>

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

that's it. two strings walk in, one int walks out 😌

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🦋 DESCRIPTION 🦋

So strcmp() compares the two strings s1 and s2, and it does it as if by calling memcmp(3). no cap, that's the entire vibe.

It's equivalent to this exactly:

memcmp(s1, s2, MIN(strlen(s1),strlen(s2))+1)

the way that it only compares up to the shorter string's length plus one?? that's the null terminator doing its lil job 🧚

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💜 RETURN VALUE 💜

Go look at memcmp(3), bestie — it's giving "see also: my sibling explains it" 🙈

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🎀 ATTRIBUTES 🎀

For an explanation of the terms used in this section, see attributes(7).

• Interface: strcmp()
• Attribute: Thread safety
• Value: MT-Safe 🔥

(no table for us today, we're doing bullets, we're keeping it cute)

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👑 STANDARDS 👑

C11, POSIX.1-2008. certified standard behavior periodt ✨

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🌈 HISTORY 🌈

POSIX.1-2001, C89, SVr4, 4.3BSD. she's been around, she's a legend, she's literally been doing this since forever 💀

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😭 CAVEATS 😭

The locale is not taken into account. So if you need a locale-aware comparison, go see strcoll(3) instead, this one is not doing that for you fr fr.

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🍓 EXAMPLES 🍓

The program below can be used to demonstrate the operation of strcmp(). Watch her work:

$ ./strcmp ABC ABC;
<str1> and <str2> are equal
$ ./strcmp ABC AB;      # 'C' is ASCII 67; 'C' - '\0' = 67
<str1> is greater than <str2> (67)
$ ./strcmp ABA ABZ;     # 'A' is ASCII 65; 'Z' is ASCII 90
<str1> is less than <str2> (-25)
$ ./strcmp ABJ ABC;
<str1> is greater than <str2> (7)
$ ./strcmp $'\201' A;   # 0201 - 0101 = 0100 (or 64 decimal)
<str1> is greater than <str2> (64)

okay quick note on that last one: it uses bash(1)-specific syntax to produce a string containing an 8-bit ASCII code, and the result demonstrates that the string comparison uses unsigned characters. not me finding that lowkey fascinating 🧚✨

💻 Program source 💻

here's the whole source, verbatim, she's adorable:

// strcmp.c
// Licensed under GNU General Public License v2 or later.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int
main(int argc, char *argv[])
{
    int res;

    if (argc != 3) {
        fprintf(stderr, "Usage: %s <str1> <str2>\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    res = strcmp(argv[1], argv[2]);

    if (res == 0) {
        printf("<str1> and <str2> are equal");
        printf("\n");
    } else if (res < 0) {
        printf("<str1> is less than <str2> (%d)\n", res);
    } else {
        printf("<str1> is greater than <str2> (%d)\n", res);
    }

    exit(EXIT_SUCCESS);
}

note the lil printf("<str1> and <str2> are equal"); on its own line and then a separate printf("\n"); — that's just how she is, we respect it 🫶

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👀 SEE ALSO 👀

• memcmp(3)
• strcasecmp(3)
• strcoll(3)
• streq(3)
• string(3)
• strverscmp(3)
• wcscmp(3)

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and that's the whole page bestie!! 💖 this one came from Linux man-pages 6.20, dated 2026-08-10, and honestly? slay. go compare some strings, you got this 🌟💅