C Programming Code Examples
C > Sorting Searching Code Examples
Binary search [string pointer array]
/* Binary search [string pointer array] */
#include <stdio.h>
#include <string.h>
static int binsearch(char *str[], int max, char *value);
int main(void) {
/* note, array needs to be sorted for bsearch... */
char *strings[] = { "bill", "chris", "jason", "randy", "trish" };
int i, asize, result;
i = asize = result = 0;
asize = sizeof(strings) / sizeof(strings[0]);
for(i = 0; i < asize; i++)
printf("%d: %s\n", i, strings[i]);
printf("\n");
if((result = binsearch(strings, asize, "randy")) != 0)
printf("`randy' found at position: %d\n", result);
else
printf("`randy' NOT found..\n");
if((result = binsearch(strings, asize, "nick")) != 0)
printf("`nick' found at %d\n", result);
else
printf("`nick' was NOT found..\n");
return 0;
}
static int binsearch(char *str[], int max, char *value) {
int position;
int begin = 0;
int end = max - 1;
int cond = 0;
while(begin <= end) {
position = (begin + end) / 2;
if((cond = strcmp(str[position], value)) == 0)
return position;
else if(cond < 0)
begin = position + 1;
else
end = position - 1;
}
return 0;
}
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