dice generating

投擲㇐個六面骰子60,000,000次 switch case

requires 2 sec

require less

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#define SIZE 7
// function main begins program execution 
int main(void)
{
unsigned int frequency [SIZE] = {0}; // clear counts
srand(time(NULL)); 
// seed random number generator
// roll die 60,000,000 times
for (unsigned int roll = 1; roll <= 60000000; ++roll) { 
size_t face = 1 + rand() % 6; ++frequency [face]; // replaces entire switch of Fig. 5.12 
}
printf("%s%17s\\n", "Face", "Frequency");
// output frequency elements 1-6 in tabular format 
for (size_t face = 1; face < SIZE; ++face) { 
printf("%4d%17d\\n", face, frequency [face]); 
}
}

// Fig. 5.12: fig05_12.c
// Rolling a six-sided die 6,000,000 times.
#include <stdio.h>
#include <stdlib.h>
// function main begins program execution 
int main( void )
{
unsigned int frequency1 = 0; // rolled 1 counter
unsigned int frequency2 = 0; // rolled 2 counter
unsigned int frequency3 = 0; // rolled 3 counter 
unsigned int frequency4 = 0; // rolled 4 counter
unsigned int frequency5 = 0; // rolled 5 counter 
unsigned int frequency6 = 0; // rolled 6 counter
unsigned int roll; // roll counter, value 1 to 6000000 
int face; 
// represents one roll of the die, value 1 to 6
// loop 6000000 times and summarize results
for (roll = 1; roll <= 6000000; ++roll) {
	face = 1 + rand() % 6; 
	// random number from 1 to 6
	// determine face value and increment appropriate counter 
	switch (face) {
		case 1: // rolled 1 
		++frequency1; 
		break;
		case 2: // rolled 2 
		++frequency2; 
		break;

		case 3: // rolled 3 
		++frequency3; 
		break;

		case 4: // rolled 4 
			++frequency4; 
			break;

		case 5: // rolled 5 
			++frequency5; 
			break;

		case 6: // rolled 6 
			++frequency6; 
			break; // optional 
			} // end switch
} // end for
// display results in tabular format 
printf( "%s%13s\\n", "Face", "Frequency" ); 
printf(" 1%13u\\n", frequency1 );
printf(" 2%13u\\n", frequency2); 
printf(" 3%13u\\n", frequency3);
printf(" 4%13u\\n", frequency4 );
printf(" 5%13u\\n", frequency5 ); 
printf(" 6%13u\\n", frequency6 );
} // end main