strncasecmp()

Compare two strings, ignoring case, up to a given length

Synopsis:

#include <strings.h>

int strncasecmp( const char* str1,
                 const char* str2,
                 size_t n );

Arguments:

str1, str2: The strings that you want to compare.
n: The maximum number of characters that you want to compare.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The strncasecmp() function compares up to n characters in two strings, specified by str1 and str2, ignoring the case of the characters.

Returns:

< 0: s1 is less than s2.
0: s1 is equal to s2.
> 0: s1 is greater than s2.

Examples:

The following code:

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

void compare( const char *s1, const char *s2 )
{
    int retval;
    
    retval = strncasecmp( s1, s2, 3 );
    if( retval > 0 ) {
        printf( "%s > %s\n", s1, s2 );
    } else if( retval < 0 ) {
        printf( "%s < %s\n", s1, s2 );
    } else {
        printf( "%s == %s\n", s1, s2 );
    }
}

int main( void )
{
    char *str1 = "abcdefg";
    char *str2 = "HIJ";
    char *str3 = "Abc";
    char *str4 = "aBCDEfg";

    compare( str1, str2 );
    compare( str1, str3 );
    compare( str1, str4 );
    compare( str1, str1 );
    
    compare( str2, str2 );
    compare( str2, str3 );
    compare( str2, str4 );
    compare( str2, str1 );
    
    return EXIT_SUCCESS;
}

produces output that looks like:

abcdefg < HIJ
abcdefg == Abc
abcdefg == aBCDEfg
abcdefg == abcdefg
HIJ == HIJ
HIJ > Abc
HIJ > aBCDEfg
HIJ > abcdefg

Classification:

POSIX 1003.1

Safety:
Cancellation point	No
Interrupt handler	Yes
Signal handler	Yes
Thread	Yes