How might I write an implementation in C of a case-insensitive version of the standard library function strcmp ? Here's how I might.
This this is often available as a nonstandard function that may be called stricmp , _stricmp , strcmpi , or strcasecmp .
See also Strings: Comparing.
#include <stdio.h>
#include <ctype.h>
int mystricmp(const char *a, const char *b)
{
for ( ; *a && *b; ++a, ++b )
{
if ( toupper(*a) != toupper(*b) )
{
break;
}
}
return toupper(*a) - toupper(*b);
}
int main (void)
{
const char *text[] = { "hello", "world", "Hello", "hell"};
size_t i, j;
for ( i = 0; i < sizeof text / sizeof *text; ++i )
{
for ( j = i + 1; j < sizeof text / sizeof *text; ++j )
{
printf("mystricmp(\"%s\", \"%s\") = %d\n", text[i], text[j],
mystricmp(text[i], text[j]));
}
}
return 0;
}
/* my output
mystricmp("hello", "world") = -15
mystricmp("hello", "Hello") = 0
mystricmp("hello", "hell") = 79
mystricmp("world", "Hello") = 15
mystricmp("world", "hell") = 15
mystricmp("Hello", "hell") = 79
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