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C/C++ Users Group Library 1996 July
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C-C++ Users Group Library July 1996.iso
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1990-07-17
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#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#define ARRAY_SIZE 1000
int test_array[ARRAY_SIZE];
int compare( int *a, int *b )
{
return( *a - *b );
}
main()
{
int i;
time_t start_time;
time_t stop_time;
for ( i=0; i<ARRAY_SIZE ; i++ )
test_array[i] = rand();
time( &start_time );
qsort( test_array, ARRAY_SIZE, sizeof(int), compare );
time( &stop_time );
printf( "%f seconds elapsed.\n", difftime( stop_time, start_time));
test_array[0] += 100;
time( &start_time );
qsort( test_array, ARRAY_SIZE, sizeof(int), compare );
time( &stop_time );
printf( "%f seconds elapsed.\n", difftime( stop_time, start_time));
for (i=0 ; i<ARRAY_SIZE-1 ; i++ )
if ( test_array[i] > test_array[i+1] )
printf( "Mismatch at position %d\n", i );
}
Demonstrating Worst-Case qsort() Performance
Figure 14