[C language] guessing numbers game

Preface

Now many games have the function of drawing lottery cards , In fact, this is similar to guessing numbers , Generate a random number , Then you guess , If you guess right, you will win the prize . Guess a certain number of times and you'll be guaranteed . To realize the small game of guessing numbers , First, let the program generate random numbers , That's what we need rand、srand and time These three functions , Secondly, we need to understand timestamp .

rand function

First look at the picture below ：

From this picture, we can see rand The return value of the function is int type , The formal parameter is empty , Its header file <stdlib.h> And its return value range is 0 To RAND_MAX. and RAND_MAX stay VS Medium is 0x7fff, Convert to binary 32767. therefore rand The range of returned random numbers is 0 To 32727.
In fact, we use rand Function can generate random numbers , Then why should we use srand Function? ？
Because only the random number generated for the first time is random , If the program is executed many times , The random number generated after the second time will be the same as that generated for the first time . This is a kind of Pseudorandom .

So only rand Functions are not enough , We need to use it. rand Function before , First use strand function .

srand function

to glance at strand function , The return value is void, Formal parameters are int Data of type , Use strand function , First of all, give strand Pass a int Data of type , According to the value passed in , The random numbers generated are also different . But this is contradictory . Before generating a random number, first pass in a random number , To solve this problem , Use a timestamp .

Time stamp

We can't give it a random number , But we can pass in time as a parameter , Time changes , The random number generated in this way is variable . How to get a timestamp ？C Language also provides us with a time Function can help us get timestamp .

time The header file for is <time.h>,time The function prototype of is a little complicated , It doesn't matter if you don't understand , Will use it . We just want to time The value of is passed as a parameter to strand function .strand The formal parameter of is unsigned int Type of , and time The return value of time_t Type of , We can cast .time The formal parameter of is a parameter of pointer type , We use it NULL That's all right. .

srand((unsigned int)time(NULL));

After solving this problem , We still have to solve rand The problem of generating the range of random numbers , We If you want to get one 1~N Between the numbers , To generate random number pairs N Take the rest +1. For the convenience of guessing numbers , The range of generated random numbers is controlled within 1 To 100. It's not easy to guess numbers at once , If you guess wrong, keep guessing , Guess right and quit . Here is the complete code .

Complete code + Program diagram

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<stdlib.h>
#include<time.h>

void menu()
{
    
	printf("|-------------------|\n");
	printf("|-----1. Play a game ------|\n");
	printf("|-----0. sign out --------|\n");
	printf("|-------------------|\n");
}
void game()
{
    
	int ret = rand()%100+1;
	int m = 0;
	while (1)
	{
    
		scanf("%d", &m);
		if (m > ret)
		{
    
			printf(" Guess the ！\n");
		}
		else if (m < ret)
		{
    
			printf(" Guess a little ！\n");
		}
		else
		{
    
			printf(" congratulations , Guessed it ！\n");
			break;
		}
	}
}
int main()
{
    
	srand((unsigned int)time(NULL));
	int n = 0;
	do
	{
    
		menu();
		printf(" Please select ：");
		scanf("%d", &n);
		switch (n)
		{
    
		case 1:
			printf(" Start guessing numbers \n");
			game();
			break;
		case 0:
			printf(" Exited \n");
			break;
		default:
			printf(" Wrong choice , Please reselect \n");
			break;
		}
	} while(n);

	return 0;
}

The program running chart is as follows ：