实验4

实验一 

不可以 一元二次方程有两个根，而函数返回值只能返回一个值。

实验二

#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;
    printf("p=%lld\n",p) ;
    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);
}

 

 总结  static局部变量只被初始化一次，下一次依据上一次结果值

实验三

#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;
}

 

 

 

 

 

实验四

#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){
    if(n==0)
    return 0;
    if(n>0)
    return 2*fun(n-1)+1;
} 

 

 

 

 实验五

#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, a, b, c, d;
    a = n;
    for (i = 1; i <= n; i++) {
        d = 2 * i - 1;
        for (b = 1; b <= (a - i); b++){
            printf("");
        }
        for (c = 1; c <= d; c++) {
            printf("%c", symbol);
        }
        printf("\n");
}
}