实验四

#include<math.h>
#include<stdio.h>

void solve(double a,double b,double c);

int main(){
    double a,b,c;
    
    printf("Enter a,b,c");
    while(scanf("%lf%lf%lf",&a,&b,&c)!=EOF){
        solve(a,b,c);
        printf("Enter a,b,c: ");
    }
    return 0;
    
} 




void solve(double a,double b,double c){
    double x1,x2;
    double delta,real,imag;
    
    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);
        } 
    }   
}     

#include<stdio.h>
long long fac(int n);

int main(){
    int i,n;
    
    printf("Enter n:");
    scanf("%d",&n);
    
    for(i=1;i<=n;++i)
       printf("%d!=%lld\n",i,fac(i));
       
    return 0;   
}


long long fac(int n){
     static long long p=1;
     
     p=p*n;
     
     return p;
} 

int main(){
    int k=4,m=1,p1,p2;
    
    p1=func(k,m);
    p2=func(k,m);
    printf("%d,%d\n",p1,p2);
    
    return 0;
}

int func(int a,int b){
    static int m=0,i=2;
    
    i+=m+1;
    m=i+a+b;
    
    return(m);
}

#include<stdio.h>

#define N 1000
int fun(int n,int m,int bb[N]){
    int i,j,k=0,flag;
    
    for(j=n;j<=m;j++){
        flag=1;
        for(i=2;i<j;i++)
           if(j%i==0){
           flag=0;
           break;
           } 
        if(flag==1)
           bb[k++]=j;        
    }
    return k;
}

int main(){
    int n=0,m=0,i,k,bb[N];
    
    scanf("%d",&n);
    scanf("%d",&m);
    
    for(i=0;i<m-n;i++)
        bb[i]=0;
    
    k=fun(n,m,bb);
    
    for(i=0;i<k;i++)
      printf("%4d",bb[i]);
      
    return 0   ; 
}

#include<stdio.h>
#include<math.h>
long long fun(int n);

int main(){
    int n;
    long long f;
    
    while(scanf("%d",&n)!=EOF){
        f=fun(n);
        printf("n=%d,f=%lld\n",n,f);
    }
    
    return 0; 
}
long long fun(int n){
    int i;
    i=pow(2,n)-1;
    return i;
} 
    

#include<stdio.h>
void draw(int n,char symbol);

#include<stdio.h>
int main(){
    int n,symbol;
    
    while(scanf("%d %c",&n,&symbol)!=EOF){
        draw(n,symbol);
        printf("\n");
    }
    return 0;
}

void draw(int n,char symbol){
    int i,j;
    for(i=1;i<=n;i++){
        for(j=1;j<=n-i;j++){
            printf(" ");
        }
        for(j=1;j<=2*i-1;j++)
         printf("%c",symbol);
         
         printf("\n");
    }
}

实验一当中，方程的根可以设计成以函数返回值的方式返回给主调函数