实验4

#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:");
    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;
}

#include<stdio.h> 
int func(int, int);

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(j==i) 
           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>
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){
    long long f;
    if(n==0)
    return 0;
    else
    f=2*fun(n-1)+1;
    return f;
}

#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 line,m;
    for(line=0;line<n;line++){
        for(m=0;m<n-line-1;m++){
            printf(" ");
        }
        for(m=0;m<=2*line;m++){
            printf("%c",symbol);
        }
        printf("\n");
    }
}