实验3

#include <math.h>
#include <stdio.h>
#include <stdlib.h>
int main() {
    float a,b,c,x1,x2;
    float delta,real,imag;
    printf("Enter a,b,c: ");
    while(scanf("%f%f%f",&a,&b,&c)){
        if(a==0)
          printf("not quadratic equation.\n");
        else{
            delta=b*b-4*a*c;
            if(delta>=0){
                x1=(-b+sqrt(delta))/(2*a);
                x2=(-b-sqrt(delta))/(2*a);
                printf("x1=%f,x2=%f\n",x1,x2);
                
            }
            else{
                real =-b/(2*a);
                imag =sqrt(-delta)/(2*a);
                printf("x1=%f+%fi,x2=%f-%fi\n",real,imag,real,imag);
                
                
            }
        }
        printf("Enter a,b,c:\n");
        
    }
    system("pause");
    return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main() {
    int guessNumber; 
    int ans; 
    
    srand((time(0))); 
    guessNumber = 1 + rand()%100;  
    
    do {
        printf("your guess number is(1~100): ");
        scanf("%d", &ans);
        if(ans < guessNumber)
            printf("%d is lower than the number.\n", ans);
        else if(ans > guessNumber) 
            printf("%d higher then the number.\n", ans); 
    }while(ans != guessNumber);
    
    printf("Congratulations. you hit it~\n");    
    
    system("pause"); 
     
    return 0;
} 

#include <stdio.h>
#include <stdlib.h>
int main() {
    int number, max, min, n;
    
    n=1;
    printf("输入第%d个数: ", n);
    scanf("%d", &number);
    max = number;
    min = number;
    
    while(n<5) {
        n++;
        printf("输入第%d个数: ", n);
        scanf("%d", &number);    

        if(max<=number)
            max = number;
        else if(min>=number)
            min = number;
    }
    
    printf("最大数为: %d\n", max);
    printf("最小数为: %d\n", min);
    
    system("pause");
    
    return 0;
} 

#include <stdio.h>
#include <math.h>
int isprime(int n);
int main()
{
    int i,n;
    n=0;
    for(i=101;i<=200;i++)
    {
        if(isprime(i))
          {
          printf("%4d",i); 
          n++;
          if(n%5==0)
          printf("\n");
           }
        
    }
    printf("\n101~200之间共有%d个素数",n);
    return 0;
    
}
int isprime(int n)
{
    int k;
    for (k=2;k<=sqrt(n);k++)
    if(n%k==0)
    return 0;
    return 1;
}

#include <stdio.h>
int main()
{
    long s;
    int t,i,n;
    t=0;
    n=1;
    printf("Enter a number:");
    scanf("%ld",&s);
    while(s>0){
    
        i=s%10;
        s=s/10;
        
        if(i%2!=0)
        {
            t=t+i*n;
            n=n*10;
            
        }
        
        
    }
    printf("new number is:%d\n",t);
    return 0;
} 

 

 

#include <stdio.h>
int main () {
    int n,i;
    float a,t,s,m;
    s=0;
    t=0;
    printf("Enter n and a :");
    scanf("%d%f",&n,&a);
    for (i=1;i<=n;i++)
    {
      t=a+t*10;
      m=i/t;
      s=s+m;
    } 
      
       printf("%f\n",s);
    return 0;
}

实验总结:

1.对于循环语句还是不怎么熟练，外循环和内循环老是搞混

2.到自己编写时会想很久，试错多次才行，还是得多练习

3.注意加分号